The number of various educational programs is increasing, _______ important roles have been realized by more and more people.

A．whose

B．where

C．which

D．that

中国金融期货交易所规定，当日结算价是指某一期货合约( )成交价格按照成交量的加权平均价。

A．最后五分钟
B．最后半小时
C．最后一小时
D．当日