Source: Friend

A recent study has concluded that, contrary to the claim of those trying to ban cigarette advertisements altogether, cigarette ads placed on bill boards and in magazines have little to no effect on the smoking habits of the smokers who views the ads. The study, which surveyed more than 20,000 smokers and solicited their reasons for continuing to smoke, found that practically no one in the survey felt that these advertisements influenced their decision to smoke.

The study's conclusion is based upon which of the following assumptions?

a) people do not switch cigarette brands based on their exposure to cigarette ads on bill boards and in magazines.

b) Cigarette ads on bill boards and in magazines do not encourage non smokers to take up the habit.

c) Banning cigarette ads altogether will encourage people to give up smoking

d) people are consciously aware of all reasons they choose to smoke

e) People who decide to smoke do so for rational reasons.

OA is D....

My doubt: In assumption question we can go for external details, in this argument study was based on the smokers reaction with cigarette ads placed on billboards and magazines. This argument failed to include non smokers reaction to the ads.

So as in option B we may assume that these ads do not encourage non smokers to take up the habit.( Assumption Q)

But in option D, it can be inferred that smokers are aware of the reasons of their smoking.( inference Q)

So, why option D but not B is correct.