单选题 We are not conscious of the extent of which work provides the psychological satisfaction that can make the difference between a full and empty life.

A、 to which
B、 in which
C、 at which
D、 by which

【正确答案】 A

【答案解析】[解析] 本题考查固定短语的用法。在句子中，which引导定语从句，to the extent of“到……的地步(或程度)”为固定用法，所以此处应选用介词to。所以，答案是A。