题目

阅读理解。 Each nation has many people who help to take care of others. For example, some high school and college students in the U.S.A. often spend many hours as volunteers in the hospitals, orphanages (孤儿院) or rest homes. They read books to the people in these places, or they just visit them and play games with them or listen to their problems. Other young volunteers go and work in the homes of people who are sick or old. They paint, clean up or repair their houses, do their shopping or mow (割，修剪) their lawns. For boys who no longer have fathers, there is an organizThis necklace is _________ of all. [　　] A. more expensiveB. the most expensive C. expensiveD. most expensive