【单选题】

Man: I thought the librarian said we could check out as many books as we need with our library cards.
Woman: That's right, but not those reference books.
Question: What does the woman mean

A．Students with a library card can check any book out.

B．Reference books are not allowed to be checked out.
C．Only students with a library card can check out reference books.
D．The number of books a student can check out is unlimite