题目选项分析

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?

【选项】When they are imprisoned, drug addicts often use their ability to manipulate other people to obtain better living conditions.