-What did your parents think about your decision?

-They always let me do ____ I think I should.[ ]

A. when      

B. that        

C. how        

D. what

点源调查的繁简程度可根据( )及其与建设项目的关系而略有不同。

A．评价级别

B．受纳水体

C．投资规模

D．地理条件