We _______the letter yesterday, but it didn”t arrive.

A．must receive

B．ought to receive

C．must have received

D．ought to have received

有一个事务T要更新数据库中某表列的值，DBMS在执行T时发现更新后的值超出了该列的值定义范围，因此异常终止了T。为了保证数据的正确性及一致性，DBMS会执行下列哪个恢复操作______。

A) undo
B) 介质恢复
C) 进程恢复
D) redo