单选题 10.On May first, in order to reduce the number of overdue books, a children's library instituted a policy of forgiving fines and giving bookmarks to children returning all of their overdue books. On July first there were twice as many overdue books as there had been on May first, although a record number of books had been returned during the interim.
Which of the following, if true, most helps to explain the apparent inconsistency in the results of the library's policy?

A、 The librarians did not keep accurate records of how many children took advantage of the grace period, and some of the children returning overdue books did not return all of their overdue books.
B、 Although the grace period enticed some children to return all of their overdue books, it did not convince all of the children with overdue books to return all of their books.
C、 The bookmarks became popular among the children, so in order to collect the bookmarks, many children borrowed many more books than they usually did and kept them past their due date.
D、 The children were allowed to borrow a maximum of five books for a two-week period, and hence each child could keep a maximum of fifteen books beyond their due date within a two-month period.
E、 Although the library forgave overdue fines during the grace period, the amount previously charged the children was minimal; hence, the forgiveness of the fines did not provide enough incentive for them to return their overdue books.

【正确答案】 C

【答案解析】Argument Construction
Situation After a library started forgiving fines and giving bookmarks to children who returned all their overdue books, the number of books returned greatly increased, but so did the number of overdue books.
Reasoning Why might the policy have simultaneously increased the number of overdue books and the number of books being returned? In order to increase both these numbers, the policy must have resulted in more books being checked out, kept past their due dates, and then returned. But why would the policy have promoted that behavior? One possibility is that it rewarded the behavior. The policy involved giving children bookmarks as rewards for returning overdue books, while removing the fines that penalized the children for doing so. If the children liked the bookmarks, they might have tried to get more of them by deliberately checking books out in order to keep them past their due dates before returning them to get the bookmarks.
A Failing to keep accurate records of the number of children would not clearly increase the number of books being returned. And the policy change did not apply to children who returned only some of their overdue books.
B This suggests that the policy had limited effects, but does not help to explain why it had apparently inconsistent effects.
C Correct. This explains how the policy gave the children a motive to check out and return more books while also allowing them to keep more of the books past the due dates.
D This restriction would have limited the number of overdue books and thus would not help to explain why that number increased.
E This suggests that the policy had little effect but does not help to explain why it had apparently inconsistent effects.
The correct answer is C.