Which two additional steps would you perform to achieve this?

You require the Oracle server to manage the undo segments and space among various active sessions automatically. You created an undo tablespace, UNDO_TBS1, in your database. Which two additional steps would you perform to achieve this? (Choose two.)

A.
Create an initial undo segment in the undo tablespace.

B.
Enable the retention guarantee for the undo tablespace.

C.
Set the UNDO_TABLESPACE parameter to UNDO_TBS1.

D.
Set the UNDO_MANAGEMENT initialization parameter to AUTO.

E.
Set the UNDO_RETENTION parameter to 900 or more.