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.