The claim of fact is based on the existing facts, regardless of whether someone likes it or not. Opinion is someone's belief in something that has not been proven or substantiated by the facts. The first statement is the claim of fact because it is scientifically proven and as such is a fact. The second statement is a matter of ethics, i.e. one's ethical conviction. The third sentence deals with the issue of problem solving, where it is not necessarily true that this is a good solution, although the reason is correct. The fourth statement is somewhat tricky, it is essentially accurate, based on facts, but obesity should be diagnosed by a doctor, and not generally give conclusions.
The answer is: A.