The RVPC user can do which of the following？（）
- A Register databases if granted the register database privilege
- B See all databases in the recovery-catalog schema
- C See all database-related metadata in the recovery catalog if they are granted access to that database
- D Unregister databases from the RVPC catalog that were not granted to the RVPC catalog owner with the grant command
- E Not be connected to with the RMAN command-line catalog parameter for backup or recovery purpose