Addiction to the nicotine in cigarettes prevents many people from quitting smoking. To make quitting easier, lawmakers in Tarnia passed legislation that will reduce the average quantity of nicotine per cigarette by half over the next five years. Since the lower a smoker's nicotine intake is, the easier it is for the person to quit, the proportion of Tarnian's attempting to quit smoking who succeed in their attempts will probably increase significantly during the next five years.

Which of the following is an assumption on which the argument depends?

a) the strength of the person's nicotine addiction only depends on the amount of nicotine that the person regularly consumes.

b) most of the cigarette smokers in tarnia would quit smoking if they were not addicted to nicotine

c) it is unlikely that many tarnians who have not already become addicted to nicotine will become addicted to nicotine at some time over the next five years.

d) tania smokers addicted to nicotine will not generally compensate for the decreases in the amount of nicotine per cigarette by smoking more cigarettes.

e) all cigarettes currently sold in tarnia contain the maximum amount of nicotine permitted by law.



I narrowed my choices down to [spoiler]A & D[/spoiler] -- but chose A, which is wrong (OA = D).

My reasoning:[spoiler] Despite the use of "only" in answer choice A (which my CR guide tells me to be wary of in an assumption question type), I felt that D was outside the scope-- the argument is about addicted smokers who want to quit smoking, not about addicted smokers in general.[/spoiler]

Could someone please help me better understand why the correct answer is what it is.

Thanks!