[求助]请教一道题目

A researcher studying drug addicts found that, on average, they tend to manipulate other people a great deal more than nonaddicts do. The researcher concluded that people who frequently manipulate other people are likely to become addicts.

which of the following, if true, most seriously weakens the researcher's conclusion?

(A)After becoming addicted to drugs, drug addicts learn to manipulate other people as a way of obtaining drugs.
(B)When they are imprisoned, drug addicts ofter use their ability to manipulate other people to obtain better living conditions.
(C)Some nonaddicts manipulate other people more than some addicts do.
(D)People who are likely to become addicts exhibit unusual behavior patterns other than frequent manipulation of other people
(E)The addicts that the researcher studied were ofter unsuccessful in obtaining what they wanted when they manipulated other people.

答案是A。我觉得这个答案怪怪的
哪位大侠给个解释？

是不是说上瘾之后，才learn to manipulate other people
weaken题设中的因果顺序：manipulate other people  --》likely to become addicts