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