You work as a database administrator at Certkiller .com. Your database is open and running in ARCHIVELOGmode. You take RMANfull backups every Sunday night. On Monday morning， while querying the user1.employeestable， you receive the following error message： 
01578： ORACLE data block corrupted （file # 5， block # 51） 
ORA-01110： data file 5：’/u01/app/oracle/oradata/orcl/example01.dbf’ 
You need to rectify the corruption while ensuring the following： 
The data file should remain online. 
The mean time to recover （MTTR） should be minimal. 
You are not using a backup control file and all the archived logs are accessible. 
Which option would you choose？（）

A. use the ALTER SYSTEM command to change the time zone
B. use the ALTER SESSION command to change the time zone
C. use the ALTER DATABASE command to change the time zone
D. set the value for the operating system variable ORA_SDTZ on the client machine
E. set the value for the operating system variable ORA_SDTZ on the database server machine

A. The members of LOW_GROUP would get more priority than those of OTHER_GROUPS.
B. The members of SYS_GROUP would get most of the CPU allocation at level 1.
C. The members of LOW_GROUP would get most of the CPU allocation because it has CPU allocation at two different levels.
D. The members of LOW_GROUP would get no CPU allocation at level1 if the members of OTHER_GROUPS are using all the CPU at level 2.
E. The members of SYS_GROUP would get no CPU allocation at level 1 if the members of OTHER_GROUPS are using all the CPU at level 2.

A. You do not need to restore all the data files.
B. You do not need to open the database with the RESETLOGS operation
C. You do not need to perform a full backup after the RESETLOGS operation.
D. You do not need to recover all the data files to the same system change number （SCN）.