FEIFEI-24 B的选项搞不懂，讨论贴里也没涉及这个选项，大家帮帮我

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.

B选项为什么不行呢，不是算给出了他因

我理解错了，which指的是Z

B是错的