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