New legislation would require a seven–day waiting period in the sale of handguns to private individuals, in order tha...

I took this question to mean that I am looking for a principle that if true, justifies the conclusion of the people opposed. So I treated it like a sufficient assumption strengthen question. If A is true, the conclusion follows. Because if law-abiding citizens rights are more worthy than criminals, then definitely their opposition would follow. I understand though that its does not represent the stimulus well. I did not like B because it says "nothing" should be done. The opposition never said nothing should be done about this issue, just that this specific legislation should not go through. Maybe they would support a modified legislation. However like A, if B is true then the conclusion does follow. So then why is A wrong and why is B right?