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CLASS 07
CANNABIS, PUBLIC HEALTH & RESPONSIBLE USE
01
What does public health mean?
Public health looks beyond one person.
In Class 06, we looked at what cannabis can do inside the human body.
Public health asks a broader question:
What happens when cannabis is used across a community or population?
That means looking not only at individual experiences, but at patterns.
PUBLIC HEALTH ASKS QUESTIONS LIKE:
WHO IS USING CANNABIS?
HOW OFTEN ARE THEY USING IT?
WHAT PRODUCTS ARE THEY USING?
ARE PATTERNS CHANGING?
WHAT BENEFITS OR HARMS ARE BEING OBSERVED?
WHO MAY BE MOST VULNERABLE?
IT IS NOT ONLY ABOUT HARM
Public health does not begin by assuming that every person who uses cannabis will experience harm.
Nor does it assume cannabis is harmless.
Instead, it tries to understand risk across a population and identify ways to reduce preventable harm.
INDIVIDUAL EXPERIENCE ≠ POPULATION EVIDENCE
One person might use cannabis without experiencing an obvious problem.
Another may experience significant unwanted effects.
Both experiences are real.
But public-health decisions cannot be based on one person's experience alone.
Researchers look for patterns across many people and over time.
REGULATION CREATES PUBLIC-HEALTH QUESTIONS
Once cannabis becomes legally accessible, governments may need to monitor things such as:
patterns of use
youth access
product potency
impaired driving
accidental ingestion
dependence and problematic use
healthcare impacts
and whether regulations are producing the outcomes they were designed to achieve.
This connects directly back to Class 03:
Regulation should be observed after it is introduced.
If evidence shows a problem, education or regulation can change.
If a feared outcome does not occur, policy should be able to learn from that too.
Public health is not about proving cannabis good or bad. It is about understanding what happens and reducing preventable harm.
Good policy watches the evidence.
02
Cannabis affects people differently
There is no single cannabis experience.
Two people can use the same cannabis product and experience different effects.
Even the same person may respond differently on different occasions.
As we learned in Class 06, response depends on more than the plant itself.
THE PRODUCT
Cannabis products can contain very different amounts and combinations of THC, CBD and other compounds.
A low-THC product and a high-THC product should not be expected to produce the same effects.
THE AMOUNT
Dose matters.
As exposure to THC increases, the likelihood and intensity of some unwanted effects can also increase.
This is particularly important with products containing concentrated amounts of THC.
THE ROUTE
How cannabis enters the body changes the experience.
INHALED cannabis generally produces effects relatively quickly.
ORAL cannabis takes longer to act and its effects can last longer.
A delayed onset can create additional risk if someone consumes more because they believe the first amount “isn't working.”
THE PERSON
Individual characteristics matter too.
Response can be influenced by factors including:
AGE
PREVIOUS EXPERIENCE & TOLERANCE
PHYSICAL AND MENTAL HEALTH
OTHER MEDICINES OR SUBSTANCES
INDIVIDUAL BIOLOGY
THE SITUATION
Where and why cannabis is being used can also matter.
An effect that may be manageable while someone is resting at home can become dangerous if that person is:
DRIVING
OPERATING MACHINERY
WORKING AT HEIGHT
or performing another activity requiring attention and coordination.
RISK IS NOT THE SAME FOR EVERYONE
This gives us an important public-health principle.
Rather than asking only:
“Is cannabis safe?”
a better question is:
Safe for whom, at what dose, using what product, in what situation?
That is a much more useful way to understand risk.
THE EQUATION EXPANDS
In Class 06 we learned:
PRODUCT + DOSE + ROUTE + PERSON = RESPONSE
Now add:
SITUATION
and we begin to understand risk.
Risk depends on context.
Cannabis does not affect every person equally, and not every pattern of use carries the same level of risk.
Understanding those differences is the beginning of responsible use.
03
Impairment
Feeling an effect and being impaired are not exactly the same thing.
Impairment means that a person's ability to perform certain tasks has been temporarily reduced.
THC can affect functions that are important in everyday life.
ATTENTION
Cannabis can make it more difficult to maintain or divide attention.
That matters when someone needs to monitor several things at once.
REACTION TIME
A person may respond more slowly to unexpected events.
Even a small delay can matter during activities requiring rapid decisions.
COORDINATION
THC can affect movement, balance and coordination.
Tasks requiring precise physical control may therefore become more difficult.
MEMORY & THINKING
Short-term memory and the ability to process information can be affected.
A person may have difficulty remembering what just happened or following a complicated sequence of instructions.
JUDGMENT
Cannabis can also influence decision-making and perception.
One particularly important problem is that:
A person may not accurately judge their own level of impairment.
Feeling comfortable or experienced with cannabis does not necessarily mean that attention, coordination or reaction time are unaffected.
THE ACTIVITY MATTERS
Impairment becomes especially important when mistakes could harm the person or someone else.
Examples include:
DRIVING
OPERATING MACHINERY
WORKING WITH TOOLS
WORKING AT HEIGHT
CARING FOR SOMEONE WHO REQUIRES CLOSE SUPERVISION
THC IS PARTICULARLY IMPORTANT
The risk of impairment is strongly associated with THC, although the degree and duration vary with dose, route, product and individual response.
Alcohol and other impairing substances can further increase risk when combined with cannabis.
Impairment is about ability—not simply how someone feels.
That distinction gives us the central lesson:
“I feel fine” does not necessarily mean “I am unimpaired.”
When an activity requires attention, judgment, coordination or rapid reactions, impairment matters.
04
Cannabis & driving
Driving requires many of the abilities THC can impair.
Driving is not a single task.
A driver must continuously watch, judge, react, coordinate and make decisions—often within seconds.
THC can interfere with several of these abilities.
WHY DOES IT MATTER?
Driving requires:
ATTENTION
Following traffic, pedestrians, signals and changing road conditions.
REACTION TIME
Responding quickly when something unexpected happens.
COORDINATION
Controlling the vehicle accurately.
JUDGMENT
Estimating distance, speed and risk.
DECISION-MAKING
Choosing the correct response while conditions are changing.
These are some of the same functions we discussed in the previous section.
FEELING READY DOESN'T PROVE YOU ARE READY
Cannabis affects people differently.
The degree and duration of impairment can depend on THC exposure, route of administration, tolerance and individual response.
This makes a simple question like:
“How many hours after cannabis can I drive?”
difficult to answer with one universal number.
Effects from edible cannabis, for example, can develop later and persist longer than effects from inhaled cannabis.
CANNABIS + ALCOHOL
Using cannabis together with alcohol can produce greater impairment than either substance alone.
This is an especially important harm-reduction message:
Do not mix intoxicants and drive.
LAW AND IMPAIRMENT ARE RELATED—but different
Driving laws vary between jurisdictions.
Some places use specific THC-related legal limits or testing systems, while others rely on evidence of impairment or different legal standards.
A legal rule, however, should not be confused with a biological guarantee of safety.
Being below a particular legal threshold does not necessarily mean a person is unimpaired.
THE RESPONSIBLE CHOICE
The principle is much simpler than trying to calculate impairment:
If cannabis has impaired you, don't drive.
Plan another way home.
Use a sober driver.
Wait until the impairing effects have passed before taking responsibility for a vehicle or other dangerous equipment.
Responsible use includes protecting other people.
Cannabis-impaired driving is not only about the person who consumed cannabis.
Passengers, pedestrians, cyclists and other road users share the consequences of driving decisions.
If an activity can seriously harm someone when judgment or reaction is impaired, don't combine it with intoxication.
05
Young people & the developing brain
Age matters when we think about cannabis risk.
The brain continues developing through adolescence and into young adulthood.
During this period, systems involved in learning, memory, attention, decision-making and emotional regulation are still developing.
That makes cannabis use among young people an important public-health concern.
THC AFFECTS BRAIN FUNCTION
As we learned earlier, THC interacts strongly with CB1 receptors, which are abundant in the brain.
While intoxicated, THC can affect:
ATTENTION
MEMORY & LEARNING
COORDINATION
JUDGMENT
These effects matter at any age, but repeated cannabis exposure during adolescence raises additional questions because the brain itself is still developing.
WHAT DOES THE RESEARCH TELL US?
Research has found associations between frequent or heavy cannabis use beginning at younger ages and a range of poorer outcomes.
But we need to be careful with the language.
An association does not always prove that cannabis alone caused the outcome. Genetics, family environment, mental health, use of other substances and social circumstances can also influence what researchers observe.
So we should avoid simplistic statements such as:
“Cannabis permanently damages every teenage brain.”
The evidence does not support talking about risk that way.
EARLIER & HEAVIER USE DESERVES MORE CAUTION
The public-health message can be much simpler:
AGE MATTERS
FREQUENCY MATTERS
THC EXPOSURE MATTERS
INDIVIDUAL VULNERABILITY MATTERS
Starting younger and using cannabis frequently—particularly higher-THC products—can increase concern about adverse outcomes.
DELAYING USE REDUCES EXPOSURE DURING DEVELOPMENT
From a public-health perspective, delaying cannabis use is therefore an important risk-reduction strategy for young people.
Legal cannabis systems commonly establish minimum-age restrictions partly for this reason.
EDUCATION SHOULD BE CREDIBLE
Young people need accurate information, not exaggerated warnings.
If education makes claims they know are untrue, they may stop trusting the information that genuinely matters.
Cannabis is not equally risky for everyone. Younger age is one factor that can increase risk.
Protect developing brains with accurate information.
Good prevention gives young people reasons—not just rules.
06
Dependence & Cannabis Use Disorder
Cannabis can become difficult to control for some people.
Not everyone who uses cannabis develops a problem.
Many people use cannabis without developing dependence.
But some people develop a pattern of use that begins to interfere with their health, responsibilities, relationships or everyday life.
When this becomes clinically significant, it may be diagnosed as Cannabis Use Disorder (CUD).
TOLERANCE
With repeated exposure, the body can adapt to cannabis.
A person may find that they need more cannabis to experience effects similar to those they previously experienced with less.
This is called tolerance.
Tolerance by itself does not necessarily mean someone has a cannabis use disorder.
DEPENDENCE
With frequent use, the body can also adapt to the regular presence of cannabis.
When someone stops after sustained frequent use, some people experience withdrawal symptoms.
These can include:
IRRITABILITY
DIFFICULTY SLEEPING
RESTLESSNESS
CHANGES IN APPETITE
ANXIETY OR LOW MOOD
CRAVING
Symptoms vary between individuals and generally improve with time.
WHEN DOES USE BECOME A DISORDER?
Cannabis Use Disorder is not defined simply by how often someone uses cannabis.
The more important question is whether use has become problematic.
Possible signs include:
difficulty controlling use
repeated unsuccessful attempts to reduce or stop
spending substantial time obtaining, using or recovering from cannabis
continuing despite problems it is causing
giving up important activities
using in risky situations
FREQUENT USE DESERVES ATTENTION
Risk is not equal for everyone.
Earlier initiation, frequent use and exposure to higher-THC products are among the factors associated with greater concern for problematic cannabis use.
But we should avoid another extreme:
Dependence is possible. It is not inevitable.
Saying “cannabis isn't addictive” ignores a real health issue.
Saying “everyone who uses cannabis becomes addicted” is equally misleading.
Good public-health education needs neither claim.
LANGUAGE MATTERS
Someone experiencing problematic cannabis use needs credible information and appropriate support, not stigma.
The objective is to recognize when cannabis has moved from something a person chooses to use into something that is causing significant difficulty in their life.
The question is not simply “Do you use cannabis?”
It is “What effect is cannabis use having on your life?”
Responsible education acknowledges dependence without exaggerating it.
Understanding risk makes informed choices possible.
07
Who may face greater risk?
Cannabis risk is not distributed equally.
A product or dose that one person tolerates may create greater concern for another.
Age, health, pregnancy, medications, personal history and the type of cannabis being used can all matter.
Some situations deserve particular caution.
PREGNANCY & BREASTFEEDING
THC can cross the placenta during pregnancy, and cannabinoids can also be present in breast milk.
Because of potential effects on fetal and infant development, major medical and public-health organizations recommend avoiding cannabis during pregnancy and breastfeeding.
This includes cannabis used for non-medical purposes. Someone considering cannabis for symptoms such as nausea during pregnancy should discuss safer treatment options with a qualified healthcare professional.
MENTAL HEALTH
Cannabis—particularly THC—can sometimes cause anxiety, panic, paranoia or perceptual disturbances.
There is also an association between cannabis use and psychosis, with concern particularly around frequent use, higher-THC exposure and people who may already be vulnerable to psychotic disorders.
This does not mean everyone who uses cannabis will develop psychosis.
It means individual vulnerability matters.
HEART & CIRCULATION
THC can temporarily affect heart rate and blood pressure.
For people with cardiovascular disease or elevated cardiovascular risk, those effects may be more significant.
MEDICATIONS
Cannabinoids can interact with other medicines.
CBD is particularly important here because it can affect enzymes involved in the metabolism of certain medications.
That means:
“Natural” does not mean “no drug interactions.”
OLDER ADULTS
Older adults may be more susceptible to some unwanted effects, including dizziness, sedation, balance problems and falls.
They are also more likely to take multiple medications, making potential interactions particularly relevant.
PEOPLE WITH LITTLE OR NO TOLERANCE
Someone unfamiliar with cannabis may respond more strongly than an experienced user to the same amount of THC.
High-potency products and delayed-onset edibles can make this especially important.
Risk depends on the person as well as the product.
This returns us to the equation we've been building:
PRODUCT + DOSE + ROUTE + PERSON + SITUATION
↓
RISK
The purpose of identifying higher-risk situations is not to frighten people.
It is to recognize that responsible cannabis education cannot give identical advice to everyone.
Know the product. Know the situation. Know when additional caution is needed.
Responsible use begins by recognizing that some circumstances carry greater risk.
08
Products create different risks
Not all cannabis products should be treated as though they are the same.
Cannabis can be consumed in many forms.
Different products can deliver very different amounts of THC, take different amounts of time to produce effects, and create different public-health concerns.
Understanding the product is therefore part of responsible use.
CANNABIS FLOWER
Dried cannabis flower is commonly smoked or vaporized.
Because cannabinoids are inhaled, effects generally begin relatively quickly.
Smoking, however, exposes the lungs to combustion products.
Inhalation also makes it possible to receive substantial THC exposure quickly, particularly with higher-potency flower.
CONCENTRATES
Cannabis can be processed into products containing much higher concentrations of cannabinoids than typical flower.
These include various extracts and concentrates.
With high-THC products, a relatively small amount can deliver a substantial amount of THC.
Higher potency can mean greater THC exposure.
That can increase the likelihood of unwanted effects, particularly for someone with little tolerance.
EDIBLES
Edible cannabis presents a different challenge.
Effects generally take longer to appear than with inhalation and can last considerably longer.
Someone may consume an edible, feel little initially and decide to take more.
Then both amounts begin producing effects.
This is why delayed onset is one of the most important things beginners should understand about edible cannabis.
LOOK-ALIKE PRODUCTS
Cannabis chocolates, gummies, cookies and drinks can sometimes resemble ordinary foods.
That creates a particular risk for:
CHILDREN
PETS
and anyone who consumes the product without realizing it contains cannabis.
STORAGE & PACKAGING MATTER
Responsible cannabis systems therefore need to think beyond what happens when someone intentionally uses a product.
Products should be clearly identified and stored securely away from children and others who should not have access to them.
Where regulated products are sold, requirements such as clear labeling, defined serving information and child-resistant packaging can help reduce preventable harm.
HOMEMADE & UNTESTED PRODUCTS
With an untested or poorly standardized product, the consumer may not know:
HOW MUCH THC IT CONTAINS
WHETHER THE DOSE IS CONSISTENT
WHAT ELSE MAY BE PRESENT
That uncertainty itself can create risk.
Product form changes the risk.
FLOWER → inhalation & combustion considerations
CONCENTRATES → potentially high cannabinoid concentrations
EDIBLES → delayed onset & longer-lasting effects
UNTESTED PRODUCTS → uncertainty about potency and contents
Responsible use begins with knowing what the product actually is.
The word “cannabis” describes a plant. It does not describe one uniform product.
09
Responsible use & harm reduction
Responsible use means reducing avoidable risk.
Harm reduction begins with a practical idea:
People make different choices about cannabis.
Good public-health education gives them accurate information that can help reduce harm.
It does not require pretending cannabis is harmless—and it does not require exaggerating its risks.
KNOW WHAT YOU ARE USING
Cannabis products can differ greatly in THC content, formulation and potency.
Where possible, use clearly labelled and tested products rather than products of unknown strength or composition.
LOWER THC MEANS LOWER THC EXPOSURE
Higher-potency cannabis can deliver more THC in a smaller amount.
For someone choosing to use cannabis, lower-THC products and lower exposure generally reduce the likelihood of some THC-related adverse effects.
More is not necessarily better.
GIVE EFFECTS TIME
Route matters.
Inhaled cannabis acts relatively quickly.
Edible cannabis takes longer.
Consuming additional edible cannabis before the first amount has taken effect can lead to unexpectedly high THC exposure.
DON'T DRIVE IMPAIRED
Cannabis can affect:
ATTENTION · REACTION TIME · COORDINATION · JUDGMENT
If impaired, do not drive, operate machinery or perform other safety-sensitive activities.
BE CAREFUL WITH OTHER SUBSTANCES
Combining cannabis with alcohol or other intoxicating substances can increase impairment and risk.
Medications can also interact with cannabinoids.
KEEP CANNABIS SECURE
Cannabis products—particularly edibles—should be stored where children and pets cannot access them.
Products that resemble ordinary sweets or foods deserve particular care.
RECOGNIZE WHEN USE IS BECOMING A PROBLEM
Pay attention if cannabis begins interfering with:
WORK OR SCHOOL
RELATIONSHIPS
HEALTH
RESPONSIBILITIES
or if reducing use becomes repeatedly difficult.
Responsible use also means recognizing when not using cannabis—or seeking help with problematic use—is the safer choice.
HARM REDUCTION IS PRACTICAL
It asks:
What is the risk?
What can reduce it?
What information does the person need?
That approach can work alongside prevention, treatment and regulation.
Responsible cannabis education does not tell people that cannabis is safe. It teaches them how risk changes—and how some risks can be reduced.
FIVE THINGS TO REMEMBER
KNOW THE PRODUCT
UNDERSTAND POTENCY
ALLOW TIME FOR EFFECTS
DON'T DRIVE IMPAIRED
STORE SECURELY
Information does not remove risk. It can help people make safer decisions.
10
Public health learns from evidence
Good cannabis policy should be able to learn.
Cannabis regulation does not end when a law is passed.
Once policies are implemented, governments, researchers and communities can observe what happens and ask:
Is the system producing the outcomes we expected?
That is where public health becomes especially important.
EDUCATION
People need accurate information about:
IMPAIRMENT
POTENCY
PRODUCTS
DEPENDENCE
HIGHER-RISK SITUATIONS
and ways to reduce preventable harm.
Good education should change as evidence changes.
MONITORING
Public-health systems can monitor patterns such as:
WHO IS USING CANNABIS
HOW OFTEN
WHAT PRODUCTS ARE BEING USED
YOUTH USE
IMPAIRED DRIVING
ACCIDENTAL INGESTION
PROBLEMATIC USE
HEALTHCARE IMPACTS
The purpose is not simply to collect numbers.
It is to understand whether meaningful changes are occurring.
RESEARCH
Monitoring tells us what is happening.
Research can help us understand why.
Researchers can examine questions such as:
What happens when cannabis availability changes?
How does product potency affect risk?
Which education strategies work?
How do different regulations affect public health?
Which groups experience greater benefits or harms?
REGULATION CAN RESPOND
Evidence can then inform decisions about:
AGE RESTRICTIONS
PACKAGING & LABELLING
PRODUCT STANDARDS
ADVERTISING
PUBLIC EDUCATION
DRIVING LAWS
and other regulatory measures.
This creates a cycle:
REGULATE → MONITOR → RESEARCH → LEARN → ADJUST
SUCCESS IS NOT ZERO RISK
No public-health system eliminates every risk.
The more useful question is whether policies can reduce preventable harm while achieving their intended objectives.
That also means being willing to recognize when an assumption was wrong.
If evidence identifies a problem, policy should respond.
If evidence does not support a feared outcome, policy should learn from that too.
Good regulation evolves.
This brings us all the way back to Class 03.
We began by learning that regulation replaces a simple prohibition with a system of rules.
Now we can add something important:
A responsible regulatory system should also measure what those rules actually do.
THE PUBLIC-HEALTH CYCLE
EDUCATE → MONITOR → LEARN → IMPROVE
Good policy watches the evidence—and changes when the evidence tells it to.
YOU NOW UNDERSTAND PUBLIC HEALTH & RESPONSIBLE USE
Cannabis affects individuals—but cannabis policy affects populations.
Public health looks beyond whether cannabis is simply legal or illegal.
It asks who is using cannabis, what they are using, how they are using it, what outcomes occur, and what can reduce preventable harm.
SIX IDEAS TO REMEMBER
RISK IS NOT THE SAME FOR EVERYONE
Product, potency, dose, route, age, health, experience and situation can all influence risk.
THC CAN CAUSE IMPAIRMENT
Attention, reaction time, coordination, memory and judgment can be affected. Feeling fine does not necessarily mean being unimpaired.
AGE MATTERS
Adolescence and young adulthood are periods of continuing brain development. Earlier and heavier cannabis exposure deserves particular caution.
DEPENDENCE IS POSSIBLE
Not everyone who uses cannabis develops problems, but some people can develop tolerance, dependence or Cannabis Use Disorder.
PRODUCTS CREATE DIFFERENT RISKS
Flower, concentrates, edibles and untested products differ in potency, onset, duration and other risks.
HARM CAN BE REDUCED
Accurate information, appropriate regulation, secure storage, avoiding impaired driving and understanding products can reduce preventable harms.
THE BIG IDEA
PRODUCT + DOSE + ROUTE + PERSON + SITUATION = RISK
And at the population level:
REGULATE → MONITOR → RESEARCH → LEARN → ADJUST
Responsible cannabis policy does not assume zero risk. It learns how risk changes and works to reduce preventable harm.
Now let's see what you remember.
CLASS 07
KNOWLEDGE CHECK
You understand the public-health fundamentals. Let's check.
10 questions · About 3 minutes · Retake anytime
1. What does public health add to our understanding of cannabis?
A. It studies only cannabis plants
B. It focuses only on individual experiences
C. It examines patterns, outcomes and risks across populations
D. It determines whether cannabis is morally acceptable
2. Why can two people using the same cannabis product respond differently?
A. Cannabis always changes chemically after purchase
B. Individual biology, tolerance, health and other factors can affect response
C. THC only affects inexperienced users
D. Everyone actually responds identically
3. Which abilities can THC impair?
A. Attention
B. Reaction time
C. Coordination and judgment
D. All of the above
4. Which statement about cannabis and driving is most accurate?
A. Experienced cannabis users are always safe to drive
B. Driving is safe once someone feels comfortable
C. A person should not drive while impaired by cannabis
D. Cannabis cannot affect driving ability
5. Why does cannabis use among young people deserve particular attention?
A. Cannabis affects only young people
B. The brain continues developing through adolescence and into young adulthood
C. Every young person who uses cannabis develops permanent injury
D. Adults cannot experience cannabis-related harm
6. Which statement about cannabis dependence is correct?
A. Cannabis can never cause dependence
B. Everyone who uses cannabis becomes dependent
C. Some people can develop dependence or Cannabis Use Disorder
D. Tolerance always means addiction
7. Why can edible cannabis create a particular risk for inexperienced users?
A. Edibles contain no THC
B. Their effects can be delayed, which may lead someone to consume more before the first amount takes effect
C. They always act immediately
D. Edibles cannot cause impairment
8. Which person or situation may warrant additional caution around cannabis?
A. Pregnancy
B. Certain mental-health vulnerabilities
C. People taking medications that may interact with cannabinoids
D. All of the above
9. Which is an example of harm reduction?
A. Assuming all cannabis products are equally strong
B. Driving if you believe you feel fine
C. Understanding product potency, avoiding impaired driving and storing cannabis securely
D. Taking more of an edible immediately when effects are not noticeable
10. What should a public-health system do after cannabis regulations are introduced?
A. Assume the regulations work permanently
B. Stop collecting information
C. Measure only cannabis sales
D. Monitor outcomes, research what happens and adjust policy when evidence supports change
RESULTS
8-10 : EXCELLENT
You understand the fundamentals of cannabis, public health and responsible use.
5-7 : ALMOST THERE
You understand the main ideas. Review the sections you missed and try again.
0-4 : TAKE ANOTHER LOOK
Return to Class 07 and review the fundamentals. There is no penalty and no limit on attempts.
CHECK YOUR ANSWERS
1 C · 2 B · 3 D · 4 C · 5 B · 6 C · 7 B · 8 D · 9 C · 10 D