We are concerned with consumer demand, the demand created by the final purchaser of goods（）

A．像他那么年轻是能够胜任这项任务的。
B．像他那么年轻是适合干这项工作的。
C．虽然他很年轻，但他适合干这项工作。
D．尽管他还年轻，但他能胜任这项工作。

A．when Kennedy was the president, he made some outstanding achievements
B．Kennedy failed his duty as the president of the United States
C．with Kennedy as the president, fewer people concerned themselves with state affairs
D．in Kennedy' s time, the United States, Russia and Cuba all had some problems