GMAT Critical Reasoning (CR) | Re: Vaccine Example SV40

C is out of scope. The passage says: virus found in mesotheliomas decades later.

So, basically the argument is talking about around, let’s say 1990. SV40 virus was found in mesotheliomas in 1990 and researchers hypothesize that this was because in 1960 some polio vaccine was contaminated with the virus.

Now, whether or not recently discovered (which means in 2016) samples of the vaccine dating from 1960 still show traces of the virus, is immaterial to the researchers' hypothesis.

---