【正确答案】 D

【答案解析】推理题。文章中反复提到“Most of the work that most people have to do is not in itself interesting，but even such work has certain great advantages．”、“Work therefore is desirable，first and foremost，as a preventive of boredom...”等句子，说明工作是有益的，因此not interesting but very rewarding是符合题意的。