Examine the following command used to perform incremental level 0 backup：   RMAN> BACKUP INCREMENTAL LEVEL 0 DATABASE；   To enable the block change tracking， after the incremental level 0 backup you issued the following command：   SQL> ALTER DATABASE ENABLE BLOCK CHANGE TRACKING USING FILE ’/mydir/ rman_change_track.f’；To perform incremental level 1 cumulative backup， you issued the following command：   RMAN> BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE；   Which two statements are true in the above situation？（）

• A、 The block change tracking data will be used only from the next incremental 0 backup.
• B、 The incremental backup will use change tracking data for accomplishing the backup.
• C、 The incremental backup will not use change tracking data for accomplishing the backup.
• D、 The block track file will scan all the blocks and create bitmap for all the blocks backed up in the level 0 backup.