—May I remind you that Mr. White is waiting outside, Mrs. Green?

—Oh, I _________ all about it.

A．forget

B．had forgotten

C．forgot

D．was forgetting

高效减水剂缓凝型外加剂中性能指标中含气量不可以为下列哪个数值（）。

A、4.5%

B、4.0%

C、3.5%

D、5.0%