College professor: College students do not write nearly as well as the

A is clearly the answer, but why are B and C necessarily wrong?

Dear CEdward
B and C can be dismissed on the reason that the professor made the generalization: If one student is poor writer then all students in the college are illiterate. We do not care whether the professor has good judgment ability or not.

For option "C" : It is talking about good teacher [ie, teaching skill] and not judging one . Hence , broad idea so can be rulled out!!.

College professor: College students do not write nearly as well as they used to. Almost all of the papers that my students have done for me this year have been poorly written and ungrammatical.

Which one of the following is the most serious weakness in the argument made by the professor?

(A) It requires confirmation that the change in the professor's students is representative of a change among college students in general. - CORRECT.

(B) It offers no proof to the effect that the professor is an accurate judge of writing ability. - WRONG. This is like C only, focusing on non-core issue.

(C) It does not take into account the possibility that the professor is a poor teacher. - WRONG. Did professor argued that he is good or bad? Not hitting the core of the argument of professor.

(D) It fails to present contrary evidence. - WRONG. Irrelevant.

(E) It fails to define its terms sufficiently. - WRONG. It's just a simple argument and need not to be complicated.

B and C might confuse some for simple reason that they might not have understood question stem properly. The question is about weakness in professor's argument not overall as presented.

Answer A.

We don't have to worry about B because we generally accept the truth of the given premises. If the professor says the writing is bad, we accept that. We only address the logic that gets us from this premise to the conclusion. As for C, there's no indication that it was the professor's job to teach these students writing and grammar. (Hopefully they've had some instruction by the time they get to college, and we don't even know what subject the professor teaches.) Therefore, we don't know whether the professor's teaching has any effect on the issue.