42.Which of the following is the most appropriate topic sentence for the paragraph below?
(A)You shouldn’t mark a book which is not yours.
(B)It is a good habit to mark youx book during reading.
(C)Many of the world，s great books are available now.
(D)Books can be cheaply bought in reprinted editions._____ Librarians (or your friends) who lend you books expect you to keep themclean, and you should. If you decide that I am right about the usefulness of marking books，you will have to buy them. Many of the world’s great books are available today，in reprint editions，at less than ten dollars.