陈向东第二章例题20,怎么想都想不明白啊

 A researcher discovered that people who have low levels of immune-system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. The researcher concluded from this experiment that the immune system protects against mental illness as well as against physical disease.

The reseacher's conclusion depends on which of the following assumption?

answer:Mental illness does not cause people's immune-system activity to decrease.

题干中研究者发现现象A:low levels of immune-system activity与现象B:score much lower on tests of mental health伴随发生。那么要推断出the immune system protects against mental illness，即
                A->B，那么首先要假设B不能推出A.即answer:Mental illness does not cause people's immune-system activity to decrease.

题干说AB两件事情相关联，所以A导致了B

这种情况下的assumption很大可能是并不是B导致了A。

满多题是这种思路的，lz记住吧！

加油！