-- Who do you think _____ such a foolish thing?

-- It _____ Tom, but I’m not sure.

A．could have done; may have been

B．could have done; must have been

C．should have done; may be

D．must have done; might have been

封闭式基金的价格受市场供求关系的影响，开放式基金的申购、赎回价格则取决于基金份额净值的大小。（　　）