You set the recovery window to seven days and the backup optimization to ON using the CONFIGURE command of Recovery Manager （RMAN）. The most recent backup of the TOOLStablespace to disk was taken on January 3. The TOOLStablespace is read-only.On February 21， when you execute a command to back up all the tablespaces to disk， you find that RMAN backs up the TOOLS tablespace also， even though the contents of the tablespace have not changed after the backup on January 3. Because there are no changes made to the TOOLStablespace， you decide that the tablespace should not be backed up by RMAN. What can you do to skip backing up the TOOLStablespace without changing the current backup optimization setting？（）

A.  configure a default device for RMAN backups

B.  temporarily disable the retention policy for RMAN backups

C.  configure automatic channel allocation for RMAN backups

D.  use the CONFIGURE command to reconfigure the recovery window to 60 days