【正确答案】 D

【答案解析】[解析] 划线词词义是“动机，动因”。
A项choice意为选择，挑选；例句：The choice rests entirely with you.这完全由你来选择。
B项idea意为主意，念头；例句：It would be a good idea to go swimming in the pond.到池塘里去游泳倒是个好主意。
C项decision意为决定，决议；例句：we can't reach a decision without our chairman.主席不在场，我们无法做出决定。
D项reason意为原因；动机。例句：That is the reason why I don't like it.那就是我不喜欢它的原因。
很明显D项正确。