应用了Helr的逻辑方法 这题很疑惑 求NN指教

87. A survey wasrecently conducted among ferry passengers on the North Sea.Among the results was this: more of those who had taken anti-seasicknessmedication before their trip reported symptoms of seasickness than those whohad not taken such medication. It is clear, then, that despite claims by drugcompanies that clinical tests show the contrary, people would be better off nottaking anti-seasickness medications.

Which one of thefollowing, if true, would most weaken the conclusion above?

A.      Given rough enough weather,most ferry passengers will have some symptoms of seasickness.

B.       The clinical tests reported bythe drug companies were conducted by the drug companies’ staffs.

C.       People who do not takeanti-seasickness medication are just as likely to respond to a survey onseasickness as people who do.

D.      The seasickness symptoms of thepeople who took anti-seasickness medication would have been more severe hadthey not taken the medication.

E.       People who have spent money onanti-seasickness medication are less likely to admit symptoms of seasickness thanthose who have not.

我选了A 但答案说是D 我觉得这个题属于相关因果drug使船员更容易晕船 那么削弱的话就找个别的会使船员晕船的原因 我是这么理解的 但答案里面说A是加强 D才是削弱 实在不解 求解答！