You configured the default backup device type as disk for RMAN backups. In your database，because of business requirements，you have to take a simultaneous duplicate backup of the data files when the RMAN BACKUP command is used.  What must you set using the RMAN CONFIGURE command to achieve this？（）  

• A、 MAXSETSIZE TO 2
• B、 DEVICE TYPE DISK PARALLELISM 2
• C、 RETENTION POLICY TO REDUNDANCY 2
• D、 DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 2