单项选择题

A. There are no backup sets with any backups of the users01.dbf datafile.
B. The users01.dbf datafile has had unrecoverable operations occur in it. It will need to be backed up or some data loss is possible during a recovery.
C. The users01.dbf datafile is corrupted.
D. The users01.dbf datafile backup exceeds the retention criteria.
E. The last backup of the users01.dbf datafile failed and must be rerun.