请教Prep-2-24

24. (28903-!-item-!-188;#058&004064)

Although exposure to asbestos is the primary cause of mesothelioma, a slow-developing cancer, researchers believe that infection by the SV40 virus is a contributing cause, since in the United States 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40.  SV40 is a monkey virus; however, in 1960 some polio vaccine was contaminated with the virus.  Researchers hypothesize that this vaccine was the source of the virus found in mesotheliomas decades later.

Which of the following, if true, most strongly supports the researchers' hypothesis?

(A) SV40 is widely used as a research tool in cancer laboratories.
(B) Changes in the technique of manufacturing the vaccine now prevent contamination with SV40.
(C) Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.
(D) In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.
(E) In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.

E是正确选项，我完全理解。

因为结论推测：美国的M慢性病是由感染SV40引起。

假设1：1960年一些美国的某种疫苗曾经受到了SV40污染。

假设2：在美国60%的M病组织中找到了SV40，而健康的组织中没有。

E是支持了假设2：在芬兰，疫苗未曾受到污染的地方，M病组织中不含有SV40。

我想问的是，为什么C不对。

因为C不是也支持了假设1吗——最近发现的1960年的这种疫苗中，依然找到了这种病毒的痕迹？是否是因为假设是要把SV40与M慢性病联系起来，但C只是证实了疫苗受到了污染，并没有联系说这种污染引起了病呢？

谢谢！

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