请教费费逻辑 no.87

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

Which one of the following, 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 by the drug companies were conducted by the drug companies’ staffs.

(C) People who do not take anti-seasickness medication are just as likely to respond to a survey on seasickness as people who do.

(D) The seasickness symptoms of the people who took anti-seasickness medication would have been more severe had they not taken the medication.

(E) People who have spent money on anti-seasickness medication are less likely to admit symptoms of seasickness than those who have not.

C corroborate the conclusion that anti-seasickness drug are not effective as expected.

c说吃药和不吃药的人对调查做出回应的可能性是一样的。说明了调查的有效性，起不到weaken的作用。

可是d不是说有seasickness sympton的人吃了要之后比没吃药之前更严重吗,这样不是support了结论(人在不服药的时候情况较好)吗?请指教