(A) suggests the teacher doesn’t have overwhelming evidence of a disastrous consequence from failing to raise the student’s grade. It MIGHT harm the student’s chances of getting an internship, but its not reasonable to think that’s overwhelming evidence it “will” have disastrous consequences. So, according to the principle, the teacher should fulfill her duty.

Unreachable conclusion. (B) concludes that the person should NOT fulfill the duty. But the principle tells us what condition is sufficient for the judgment that you SHOULD fulfill your duty. That doesn’t support an argument that concludes one should NOT fulfill the duty. (If you think it does, you’re confusing sufficient and necessary conditions.)

Unreachable conclusion. (C) concludes that the person should NOT fulfill the duty. But the principle tells us what condition is sufficient for the judgment that you SHOULD fulfill your duty. That doesn’t support an argument that concludes one should NOT fulfill the duty. (If you think it does, you’re confusing sufficient and necessary conditions.)

(D) involves multiple conflicting duties. In addition, the psychiatrist doesn’t have overwhelming evidence of disastrous consequences from fulfilling either duty. So the principle would have the psychiatrist fulfilling both duties. (D) contradicts this and advocates breaking one of the duties and fulfilling the other.

(E) involves a conclusion about waiting to fulfill a duty. But the principle doesn’t allow us to prove that someone should wait to fulfill a duty. (It doesn’t matter whether you think (A) is a less than perfect answer. Nothing in the principle allows us to conclude that someone should wait before fulfilling a duty. So (E) cannot be correct.)