When people are told that some behavior is common, they are more likel

OA please?
In my opinion, C is correct. Even though got a bit confused between C and D, but I chose C over D as D only talks about littering example while the conclusion is pretty generic.

Can someone please explain why the answer is A
I am still hooked on option C

The argument tries to tell that whether a behavior is depicted from a bad or a good sight, the amount of times it is brought to people's attention decides whether people will repeat that behavior.

The conclusion basically says that in order people to not repeat the bad behavior the ads should avoid showing something negative in vast quantities.

We should weaken the argument. The answers B and D are discussing specific examples, which still leave the argument strong enough for the other cases.

E. In a study, the most effective anti-littering advertisement featured a pristine public park with children playing in the background. This choice does not anyhow tell that the bad example shown in the ads affect people positively.

C. People who watch public service advertisements are typically aware that actors are merely pretending to engage in the disapproved behavior.

The first sentence of the stimulus tells us that the behavior that becomes common because of a mass spread is disapproved by the society. We should already know that people knowingly repeat the bad behavior, hence their knowledge about the actors' commitment to the advertised behavior should not deny the fact that if people are fed by these ads "enough" they will repeat the behavior advertised anyway.

A. In a study, the most effective anti-smoking advertisement featured a person smoking amidst a disapproving crowd.

This option destroys the whole argument. The smoker, who suggests a negative behavior, smokes among those who disapprove the action. The ad was effective means that the people watching the ad followed not the smoker but the society. Accordingly, the premises and the conclusion fall apart.

I understand why A is right. Can someone explain how to eliminate C, since C too weakens the argument effectively.