好心的过路人啊，帮我讲讲狒狒逻辑的第21题行吗？

风林火山

21. Historian: We can learn about the medical history of individuals through chemical analysis of their hair. It is likely, for example, that Isaac Newton’s psychological problems were due to mercury poisoning; traces of mercury were found in his hair. Analysis is now being done on a lock of Beethoven’s hair. Although no convincing argument has shown that Beethoven ever had a venereal disease, some people hypothesize that venereal disease caused his deafness. Since mercury was commonly ingested in Beethoven’s time to treat venereal disease, if researchers find a trace of mercury in his hair, we can conclude that this hypothesis is correct.
Which one of the following is an assumption on which the historian’s argument depends?
(A) None of the mercury introduced into the body can be eliminated.
(B) Some people in Beethoven’s time did not ingest mercury.
(C) Mercury is an effective treatment for venereal disease.
(D) Mercury poisoning can cause deafness in people with venereal disease.
(E) Beethoven suffered from psychological problems of the same severity as Newton’s.

这题就没看懂，为什么选择B啊？

顺天府府尹

历史学家说可以通过分析头发来推断个人的病史．比如说Isaac Newton的精神问题是由于汞中毒；并且在他的头发里发现了汞．现在来研究贝多芬的头发．尽管没有明确的证据说贝多芬有venereal disease，但是有人推断说是因为venereal disease导致了他的耳聋．因为在贝多芬时代汞被广泛用于治疗venereal disease，所以如果研究员在他的头发里发现了汞，那么这个推断就成立．

题目有一个推断：汞推出venereal disease

Ｂ如果在贝多芬时代所有人都注射了汞，那么也就不能由汞得出venereal disease

风林火山

谢谢你的回答