You are working on a database that must be functioning 24 hours a day， 7 days a week. The databaseis configured in ARCHIVELOG mode.  Which two options do you have for performing user-managed backups（）

• A、You can perform consistent backups only.
• B、You can perform a complete database backup without shutting down the database instance.
• C、You can back up data files only when all data files have the same SCN recorded in the control file.
• D、You can back up only those data files whose headers are frozen by using ALTER TABLESPACE BEGINBACKUP or ALTER DATABASE BEGIN BACKUP commands.