请教OG10 48

The researcher’s conclusion depends on which of the following assumptions?

A.      High immune-system activity protects against mental illness better than normal immune-system activity does.

B.      Mental illness is similar to physical disease in its effects on body system.

C.      People with high immune-system activity cannot develop mental illness.

D.     Mental illness does not cause people’s immune-system activity to decrease.

E.      Psychological treatment of mental illness is not as effective as is medical treatment.

想问一下这道题目，我觉得条件里面说了mental illness，但是结论里面却有physical illness，所以assumption也应该有physical illness啊？为什么答案是D啊？谢谢大家。

也错了,觉得有点绕

考虑选B

B.      Mental illness is similar to physical disease in its effects on body systems.(没说immune-system ,应该包括immune-system ,如果说similar,那也该有两种:1 Mental illness causes people’s ( body systems)immune-system activity to decrease like physical disease不行. Mental illness does not cause people’s( body systems) immune-system activity to decrease like physical disease 可以.)

D.     Mental illness does not cause people’s immune-system activity to decrease.

我是这样理解的：

前提是观察到一种现象，immune system和mental illness有某种关系

预期结论是immune system会影响mental illness

D想表达的意思是，事实上两者的相关性也有可能是mental illness为因、immune system为果造成的。所以D就排除了这种情况，使得预期结论可以成立

嗯哪，我也这么想的，因为第一句话只是说明了immune system和mental illness的相关性，相关不代表因果，更加无法判断谁是因谁是果（GMAT的逻辑很多是这样的）。

我也选得B，不过如果一定要解释D的话，就是D实际是个逆否命题，Mental illness does not cause people’s immune-system activity ！

mental illness 推 immune-system 是逆；

don't 是否，

所以应该是真命题！