GWD10 Q9

alex2610

Q9:Although exposure to asbestos is the primary cause of mesothelioma, a slow-developingcancer, researchers believe that infection by the SV40 virus is a contributing cause, sincein the United States 60 percent of tissue samples from mesotheliomas, but none fromhealthy tissue, contain SV40. SV40 is a monkey virus; however, in 1960 some poliovaccine was contaminated with the virus. Researchers hypothesize that this vaccine wasthe 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 preventcontamination 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

是E还是C呢？个人觉得选E额。。我觉得结论中关键强调的是source，而C选项只是在强调60年的V里含有virus，对于结论好像没有作用，而E很明显是一个无因无果的支持选项。。还请各位帮看看吧~~

sdcar2010

E supports the conclusion since it confirms: No contamination of the polio vaccine --> No SV40 in mesotheliomas. A contrapositive of the this logic chain is : SV40 in mesotheliomas --> contamination of the polio vaccine.  Or in GMAT language, contamination of the polio vaccine is necessary (source) for SV40 found in mesotheliomas.