用影响价格和社会折现率等参数来评价项目的可行性，是( )评价。

A．财务

B．社会

C．风险分析

D．国民经济

It was playing computer games_______ cost the boy plenty of time______ he ought to have spent doing his homework.    

A．that; that

B．which; that

C．which; when

D．that; when