A. When a successful backup is recorded in the RMAN repository， then a backup of the current control file is performed.
B. When a structural change is made to the database， then a backup of the current control file is performed.
C. When a successful backup is performed in the RMAN repository， then a backup of the spfile is performed.
D. When a structural change is made to the database， then a backup of the alert log file will be performed.

A. The backups consist of backup pieces.
B. The datafiles can be multiplexed within the backup.
C. The backups can be stored only on the disk.
D. While performing the backup across a network， the network bandwidth is reduced.