You configured the Flash Recovery Area （FRA） for your database. The database instance is runningin ARCHIVELOG mode. The default location for the archived redo log files is the Flash Recovery Area.  Which two files are removed automaticallyif the space is required in the FRA as per the retention policy（）

A. flashback log files

B. backups that have become obsolete

C. copies of the data files and control files

D. archived redo log files that have multiple copies in a different archive location and not backed up