You executed the following command in Recovery Manager （RMAN）：  RMAN> RESTORE CONTROLFILE；  Which operation must you perform before this command is executed？（） 

• A、back up the control file to trace
• B、bring database to the MOUNT state
• C、open a connection to the RMAN recovery catalog， which contains the RMAN metadata for the target database
• D、set the database ID （DBID）， but only if the DB_NAME parameter associated with the target database is unique in the recovery catalog