Using the command shown here， what time format must you specify to recover the database until a point-in-time？（） 
SQL> RECOVER DATABASE UNTIL TIME ’<time format>’；

A.It improves usability by enabling you to reuse the scripts to perform recovery operations.
B.It detects block corruption while restoration and recovery operations.
C.It enables you to perform block media recovery.
D.It is capable to recover through unrecoverable operations， with only full database backups.

A.SET AUTORECOVERY ON
B.SET RECOVERY ON
C.SET AUTO ON
D.You cannot enable automatic media recovery.