24. The interstitial nucleus, a sub-region of the brain’s hypothalamus, is typically smaller for male cats than for female cats. A neurobiologist performed autopsies on male cats who died from disease X, a disease affecting no more than .05 percent of male cats, and found that these male cats had interstitial nuclei that were as large as those generally found in female cats. Thus, the size of the interstitial nucleus determines whether or not male cats can contract disease X.

Which one of the following statements, if true, most seriously weakens the argument?

A. No female cats have been known to contract disease X, which is a subtype of disease Y.

B. Many male cats that contract disease X also contract disease Z, the cause of which is unknown.

C. the interstitial nuclei of female cats who contact disease X are larger than those of female cats who do not contract disease X.

D. Of 1,000 autopsies on male cats that did not contract disease X, 5 revealed interstitial nuclei larger than those of the average male cat.

E. The hypothalamus is known not to be causally linked to disease Y, and disease X is a subtype of disease Y.

E is the best answer. Disease X is the subtype is disease Y, if disease Y has no link with hypothalamus, X must have no link with hypothalamus.

上面是答案和解释。

可是我认为C能很好地weaken呀，不是说明了是X使得脑袋变大，而不是脑袋大就能得X。为什么不对呢？

对于E我不是很理解地说。

BTW：大家做test2感觉如何？我觉得比较难地说，而且我超时5分钟。