Why is the anwer E and not C? Any help is appreciated.

C restates that vaccine was contaminated. we have to support that this contaminated vaccine was source of the SV4 virus in mesotheliomas samples.

E serves this better.

please post this problem IN TEXT FORM in the forum.

forum rules = don't use image posting unless you're posting something that CAN'T be rendered on the forum (i.e., graphics, diagrams, etc. for math problems). there is never any good reason to post a verbal problem as an image; just type the words. (this is for the benefit of both students and instructors who connect to the forums on lower-bandwidth connections)
thank you.