Critical Reasoning (CR) | Re: The human body s blood vessels and veins are designed to

Hi,

Can an expert provide a detailed explanation for this question?
And specific questions I have here are:

1. I initially thought that it would be A or B because you can't develop a medication without having an understanding of its mechanisms. Am I wrong to think that?

2. The part about 'blocking receipt of any messages of histamine to blood vessels' through me off a bit. Does this part have any actual significance in cracking this problem, or is it just an unnecessary info on about 'developing