The manager promised to keep me _____ how our business was going on.[ ]

A. informing of    

B. informed of    

C. to inform of    

D. on informing

（）指省资金中心集中接入大小额支付系统、农信银系统和银联系统，为全省农村信用社办理与外部机构之间的资金往来清算。

A.外部清算

B.内部清算

C.逐级清算

D.集中清算