You need to perform a block media recovery on the tools01.dbf data file in the SALES database by using Recovery Manager (RMAN).Which two are the prerequisites to perform this operation？（）

A.You must configure block change tracking file

B.You must have first level 1 backups for RMAN to restore blocks

C.You must ensure that the SALES database is mounted or open

D.You must have full or level 0 backups for RMAN to restore blocks

E.You must take the tools01.dbf data file offline before you start a block media recovery