－Why didn’t you go to the cinema with us this afternoon, Jim?

－Because I ______ at the station for my uncle from Beijing at that time.

A．was waiting

B．have waited

C．am waiting

D．will wait

下图为微生物代谢调节的两种情况。请据此回答：

两图都是代谢调节的一种形式它与（）的调节同时存在，并密切配合，起协调起用。