Which two are true about changing the LOCAL_UNDO_ENABLED property to false in a CDB? (Choose two.)

[answerhappygod]

Which two are true about changing the LOCAL_UNDO_ENABLED property to false in a CDB? (Choose two.)

A. After the change, only a common user with the required privilege can create an undo tablespace in CDB&ROOT.
B. Any new PDB and existing PDBs are automatically configured to use the default undo tablespace in CDB$ROOT.
C. After the change, only one undo tablespace can exist in CDB$ROOT.
D. After the change, any user with the required privilege can create an undo tablespace in the PDBs. E. Undo tablespaces existing in PDBs must be dropped before the change. F. After the change, each existing PDB has to be reopened for the new undo mode to take effect.