Every Sunday the Unix system administrator has a job that executes a full backup of the entire Unix system your database is on. Is this backup usable for backup and recovery of your database？（）  

• A、 Yes， if the database is in ARCHIVELOG mode
• B、 Yes， if the database is in NOARCHIVELOG mode
• C、 No， the backup is not usable in any way
• D、 Only if the ENABLE_ONLINE_BACKUP parameter is set to TRUE