You are using the control file to maintain information about the database backups that are being performed by Recovery Manager (RMAN). Identify two scenarios is which you must have a recovery catalog.（）

• A、To store the backup information of multiple database
• B、To restrict the amount of space that is used by the backups
• C、To maintain a backup for a certain time is set by the CONTROL_FILE_RECORD_KEEP_TIME parameter.
• D、To list the data files that were in a target database at a given time by using the AT option of REPORT SCHEMA command.