听力原文：W: Look, I'm sorry, but the books for Chem. 100 aren't in yet.
M: Why not？ School started last week.
W: I really don't know. Maybe the professor ordered them late, or the publisher ran out of them and they are on back order.
M: This is awful. I'm worried about this course anyway. I didn't do that well in chemistry in high school.
W: I know what you mean. Did you check the used book section？
M: Yes. No luck there.
W: Okay. Look, why don't you go over to the library？ I'll bet that the professor put at least one copy on reserve.
M: Do you think so？ That would be great. At least I could make copies of the pages that I need until the books come in. Oh, wait. If there's only one copy, everyone will be trying to do that.
W: True. Well, we do have a bulletin board. You could put a notice up saying that you are looking for a book for Chemistry 100, and maybe someone who has it will want to sell it directly to you. Do you have a phone in the dorm？
M: Yeah. I'll just put my name and phone number on the notice. That's a great idea! Where's the bulletin board？
W: By the T-shirts and clothing near the front door. Oh, and be sure to put down the exact title of the book, too, because they don't always use the same one.
M: Thanks. You've been a big help.
(20)

A notice on the bulletin board.
B. A book for a class the man is taking.
C. A chemistry class that is being taught.
D. The library reserve desk.