费费24. The interstitial nucleus, a subregion 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 who 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 who 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. 答案E，我选D. 设 A： interstitial nucleus B: disease X C: brain’s hypothalamus, D: disease Y 其中A是C的 subregion, B是D的subtype。
选D的理由：文中的结论是interstitial nucleus （A）的大小决定了mail cats是否得X（B），证据是autopsies显示患X的male cats的size of interstitial nucleus都大于没有得X的male cats. 而选项D给出相反的autopsies，即没有患X的male cats中有5个的size of interstitial nucleus大于正常的male cats。虽然比例很小，仅0.5％，但足以推翻结论中的“determine”这一关键词了。
