C

题目分析：考查形容词短语。Be occupied with…忙于…；本题使用了形容词短语occupied with his school work 来修饰主语the boy就相当于="who" was occupied with….。句意：那个男孩，整天忙着学校的作业。感觉很累，想有一天的时间来好好休息。故C正确。

点评：本题使用形容词短语对名词进行修饰限制，形容词短语occupied with his school work 来修饰主语the boy，该结构就相当于一个定语从句。