A、Travel. B、Mystery. C、History. D、Poetry. B细节题。对话中只提到了Mystery和Poetry，因此排除A和B项。而题目问的是男士发现了哪种书，故选择Mystery，而poetry book是女士的选择。

W: I enjoy going through second-hand bookstores, don’t you? It’s interesting to see what people used to enjoy reading. Did you see this old book of children’s stories?
M: Some of these books aren’t so old though. See? This Mystery was published only six years ago: It cost 75 cents. You can’t beat that.
W: Hey, look at this!
M: What! Are you getting interested in 19th century poetry all of a sudden?
W: No. Look here. Someone gave this book as a present and wrote a note on the inside of the front cover. It’s dated 1893. Maybe it’s worth something.
M: Everything on that shelf is worth 50 cents.
W: But if this is the signature of someone who is well known, it might bring a lot more.  I hear Shakespeare’s signature is worth about a million dollars.
M: Oh? I can hardly read what that one says. Who wrote it?
W: The name looks like "Harold Dobson." Maybe "Dobbins"? Wasn’t he a politician or something? I’m going to buy this book and see if I can find a name like that in the library.
M: Good luck. Your poetry book may make you rich, but I’ll bet my 75-cent Mystery is a good buy.