You executed the following command in Recovery Manager （RMAN） against your Oracle 10g database：RMAN> REPORT NEED BACKUP days 3；What would be the output of this command？（）
- A a list of files that require a backup within three days
- B a list of files that have not been backed up for three days
- C a list of files that RMAN recommends be backed up only once in every three days， based on low volatility
- D a list of files for which a backup has already been performed and may need a backup after three day