My friend, who ________ on the International Olympic Committee all his life, is retiring next month.

A.served

B.is serving

C.had served

D.has served

答案及解析： D

解析：

根据主句中谓语部分(is retiring next month)可判断本句要表达的是现在的情况，因此定为现在时，排除A、C两项，而进行体的B项表未完性、暂时性，不合本句要求，故D项正确。