After a number of days set by the parameter CONTROL_FILE_RECORD_KEEP_TIME， the information in the control file is overwritten by RMAN. What is this parameter’s default value？（）

A.Shut down the database.
B.Set the appropriate parameters in init.ora file.
C.Start the database in NOMOUNT state.
D.Issue the ALTER DATABASE ARCHIVELOG command.
E.Open the database.
F.Take a full closed backup.

A.16KB
B.32KB
C.64KB
D.128KB

A.Recover Manager （RMAN） utility
B.Import utility
C.Export utility
D.O/S backup command