Which three statements are true about using flashback database in a multitenant container database(CDB)?（）

A. The root container can be flashed back without flashing back the pluggable databases (PDBs).

B. To enable flashback database, the CDB must be mounted.

C. Individual PDBs can be flashed back without flashing back the entire cdb.

D. The DB_FLASHBACK RETENTION_TARGET parameter must be set to enable flashback of the cdb.

E. CDB can be flashed back specifying the desired target point in time or an SCN, but not a restore point.