Joan got A's on all her homework assignments, so if she had gotten an

Official Explanation

The argument states that if Joan got an A on the term paper, then she will be able to pass the course without doing the class presentation. Since she didn’t get an A on the paper, the author concludes that she needs to do the class presentation to pass the class. Note, however, that the statement “If A on the paper, then no presentation” doesn’t tell us anything about what happens if Joan doesn’t get an A on the paper. It could be that she won’t need to do the presentation regardless of her paper grade.

(B) sums up this objection.

(A) introduces as a possibility the necessity of getting an A on either the paper or on the presentation to pass the class. There are no grounds for this assertion, and it doesn’t directly affect this argument anyway. Since the argument deals specifically with the necessity of the class presentation, we certainly couldn’t say, as (C) does, that it ignores this factor. (D) simply restates the conclusion of the argument, while (E) discusses the possibility, irrelevant here, that some students get A’s on their papers and still fail the course. Since Joan didn’t get an A on her paper, we don’t really care about that group of students.