求助GMAT LSAT LR中的一道题目

        Smokers of pipes or cigars run a distinctly lower risk to their health than do cigarette smokers. However, whereas cigarette smokers who quit smoking altogether sharply reduce their risk of smoking-related health problems, those who give up cigarettes and take up pipes or cigars remain in as much danger as before.

Which one of the following, if true, offers the best prospects for an explanation of why the two changes in smoking habits do not both result in reduced health risks?

(A) Smokers of pipes or cigars who quit smoking thereby reduce their risk of smoking-related health problems.

(B) Cigarette smokers who quit smoking for a time and who then resume cigarette smoking do not necessarily reduce their risk of smoking-related health problems.

(C) The kinds of illnesses that smokers run an increased risk of contracting develop no earlier in cigarette smokers than they do in smokers of pipes or cigar.

(D) At any given period in their lives, virtually all smokers smoke either cigarettes exclusively or cigars exclusively or pipes exclusively, rather than alternating freely among various ways of smoking.

(E) People who switch from cigarette smoking to smoking pipes or cigars inhale smoke in a way that those who have never smoked cigarettes do not.

The answer is E.

本来选择的C。但仔细读下来觉得C和E似乎都不能解释。所以想请NN们解释下。谢谢啦

题目关心的是 为什么吸过cigarette的人改抽cigar（按理应该risk减小）后risk没有减小。 E解释了这一点， 因为抽过烟的人改抽cigar后和一般人抽cigar的方式不同，所以不像一般人那样risk较小. C 其实是说cigarette最多和cigar一样， 不能解释题目中的puzzle。