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I cannot for the life of me figure this out, it does not make any sense to me.

The argument follows that the investigators personal impression was that these people(Geminis) were more sociable and extroverted and the test confirmed that. How then is this not a circular argument, meaning shouldn't the answer be it presuppose what it sets out to prove?

I thought all the answer choices were wrong, I honestly think this question was written improperly and therefore makes no sense. Or I just lack the general understanding of this question. Please help. Thank you.

For future reference, use this site (http://www.manhattanlsat.com/forums/) for help on LR and stuff.

As for the question on hand-

I'm not quite sure where you're getting the impression that the investigators set out with the thought that Geminis were more sociable and extroverted.

The stimulus states that the investigators found a couple of Geminis who were willing to be interviewed, and found them to be more sociable and extroverted than normal people. On the basis of this information, the investigators then concluded that astrological birth signs influence one's personality.

The obvious question then is "What if there were Geminis who weren't willing to be interviewed? What about them?

The stimulus has you thinking in this way by its use of volunteers. If it's volunteers, then you could imagine that there are many who declined to volunteer. Ergo, any conclusion reached cannot be objective.

A- Doesn't matter at all. We have no cause to believe that who administered the test matters at all.
B- Even if we took this to be true, it has no influence whatsoever on the information given in the stimulus, or the reasoning we see. Ergo, it's wrong.
C- Again, irrelevant to the reasoning presented in the stimulus.
D- Proportions doesn't matter here.
E- Matches the question I asked above.