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】After becoming addicted to drugs, drug addicts learn to manipulate other people as a way of obtaining drugs.