How does the use of いかんによっては in this question determine one answer over another?

Question

In my JLPT practise book, in a section explaining the use of `いかんによっては`, which roughly means "depending on", they have the following question: > 学生{がくせい}：先生{せんせい}、台風{たいふう}が近{ちか}づいていますね。明日{あした}のゼミは休講{きゅうこう}ですか？ > > 先生{せんせい}：そうですね。台風{たいふう}のコースいかんによっては`______` > > A: 休{やす}みです。　B:　決{き}めましょう。 I chose the answer B, thinking it roughly meant, "We will decide depending on the course of the typhoon." However, according to the book, the correct answer is A, which is translated as, "depending on the path it might be a holiday." *(The English translations in this book are not so smooth.)* Both make logical sense to me, but, despite what the book says, I can't help but feel that B makes more sense because the path of the typhoon is uncertain, and therefor so is the decision about the seminar. Thus, "let's wait and decide." Why is A the correct answer?

Answer 1

Choice A pinpoints one of the possibilities that may come about, while B does not (it's more abstract). This particular grammar point (especially the use of は) requires that you outline one of the possible outcomes in the second half of the sentence. Therefore, you could also theoretically say 「台風のコースいかんによってはゼミがあります。」, but the teacher's response in the example is more appropriate since she/he is responding directly to the student's concern about class being cancelled.