PT 57, S3, 11 - Many vaccines create immunity to

[tian.z.zheng]

I have no clue why A is the right answer..could someone please share their thoughts?

Thanks.

[aileenann]

Good question. Of course it's always important to understanding why the answer is correct, in addition to knowing why the incorrect answers are not.

This question is asking us to weaken the doctors' claim, which we can do either by challenging an assumption the doctor is making or choosing an additional premise that strongly undermines the doctors' argument. Here, (A) does the latter by suggesting that while exposure to a virus works for some disease, it does not appear to be the case for Hepatitis E. The proof that it is not the case for Hepatitis E is that lots of people who catch it do so after having already been exposed to the virus. Hence the mechanism does not seem relevant, which undermines the doctors' conclusion.

[tian.z.zheng]

Great. I misread the question. Thanks.