Critical Reasoning

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 thesource 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.

[spoiler]OA: Will be posted later[/spoiler]

'E'

m confused between 'E' and 'C'.....so help please

IMO E

if X occurs only then Y occurs (60 percent of tissue samples from mesotheliomas,contain SV40)

Strengthener would be : If X does not occur Y will never occur
(samples from mesotheliomas do not contain SV40 because polio vaccine was never contaminated)

smackmartine wrote:IMO E

if X occurs only then Y occurs (60 percent of tissue samples from mesotheliomas,contain SV40)

Strengthener would be : If X does not occur Y will never occur
(samples from mesotheliomas do not contain SV40 because polio vaccine was never contaminated)

Hi Smackmartine,

Any specific reason for rejecting option C???????

IMO C, Pl explain if otherwise

Stimulus says Y (SV40 or sumthng) causes diesease X
we need an answer choice which explicitly states that the virus is causing the diseases and it is not other way round.
option C leaves open the possibility tht may be the disease sitself is causing the virus, thn we cant blame it on the virus to cause the diseases.
E eliminates this possibility saying uncontaminated vaccines do not contain the virus. so the diseases does no cause the virus.

hope my explanation is clear

Researchers hypothesize that this vaccine was thesource of the virus found in mesotheliomas decades later.

So doesn't E contradict ?

rk10 wrote:Researchers hypothesize that this vaccine was thesource of the virus found in mesotheliomas decades later.

So doesn't E contradict ?

the contaminated vaccine was the source so E perfectly says that the uncontaminated vaccine is not a source. E does not contradict anythng. it would have contradicted if E said: even the uncontaminated vaccines have the virus. then our conclusion fails(which says virus caused the diseases). it would then mean the disease cuased virus