一道简单的assumption题目，not+weaken，可是怎么就钻进胡同去了呢？

狒狒的一道题目：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.

答案是B 

疑问：答案中的not去掉之后对文章所起的作用是使得文章成立，所以应该是没有Not才对吧？？？

还有，这个关some people 什么事情啊？

not+weaken， 钻进胡同里面去了。。。。取非后变成加强了。。不是削弱了。。。

？？急？

答案错误还是我理解错误