设关系R是4元关系，关系S是一个5元关系，关系T是R与S的笛卡儿积，即T=R×S，则关系T是 ______ 元关系。

A．9

B．11

C．20

D．40

Emma failed her exams, I think she should work hard.

-I agree. ___________ she does, she'll get good grades. [ ]

A. If

B. Because

C. Before

D. Though