View the Exhibit and examine the RMAN commands. 
Which statement describes the effect of a backup retention policy on the backup of a backup set?
A.Either all the copies of a backup set are obsolete or none of them are as per the retention policy.
B.The copies of the backup will be reported as obsolete under a redundancy-based backup retention policy.
C.The copies of the backup will be reported as obsolete under a recovery window-based backup retention policy.
D.All the copies of the backup set are counted as one instance of a backup and will deleted in backup set exceeds the redundancy-based backup retention policy.
遵循保留策略或者没过期的在report命令中会有返回信息。