Let's take a look and try not to yawn..
The conclusion of this argument is that the most irresistible cause of yawning is seeing someone else yawn. Why? Because pop culture historians say that this belief is common all over, both today and previously.
There are two gaps that I see. For one, are we to believe these historians? The conclusion assumes we do. Also, just because everyone says something is X, does it mean it actually is X? Perhaps everyone thinks we yawn mostly because we see others yawn, but they forget that we generally yawn because we're tired! The conclusion is establishing a scientific fact, but the premise is popular opinion. (D) points out this issue.
(A) is not true - the conclusion is different than the premises.
(B) is tempting! I had to think a while about why this one is wrong. Go ahead and fill in the blank to make this answer perfect:
It cites the evidence of _______________ in support of a claim that lies outside their area of expertise.
We should put "people" in there, not "historians." The argument doesn't cite the historian's statement as the evidence, it's the opinions of all the people, which the historians happen to convey (and the argument states, "if we are to believe them").
(C) is incorrect because the evidence is not based on a limited number of cases.
(E) is tempting if you think the conclusion is that seeing others yawn is the
only cause. But the argument is that it's the most irresistible one.
Does that clear it up?