You want to back up a database such that only formatted blocks are backed up. Which statement is true about this backup

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You want to back up a database such that only formatted blocks are backed up. Which statement is true about this backup operation?

A. The backup must be performed in mount state.
B. The tablespace must be taken offline.
C. All files must be backed up as backup sets.
D. The database must be backed up as an image copy.