这道答案到底是E还是C呀？

frankzhiwei

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

这题做的时候查的答案是C，可是记得以前做过答案是E，到底是那个呀？谁能帮忙解释一下，谢谢~

colasama

答案应该是E
要support的hypothesis是"vaccine中的SV40是名叫mesotheliomas中病毒的根源"
C只是确定了vaccine中的确有SV40，而没说“mesotheliomas中的SV40就是来自vaccine里的SV40”

E则是明确的逆否命题，用没有污染的vaccine，mesotheliomas就里就没有SV4O，反证了“mesotheliomas中的SV40来自vaccine”

labellor

http://forum.chasedream.com/GMAT_CR/thread-78495-1-1.html

u can take a look.

sdcar2010

E is the answer.