You work as a database administrator for Supportcenter.cn. You want to create your database with the automatic undo management feature enable.Which two tasks must you perform to achieve this？（）

• A、Set the UNDO_RETENTION parameter to AUTO.
• B、Create an initial undo segment in undotablespace.
• C、Set the UNDO_RETENTION parameter to 900 or more
• D、Set the initialization parameter UNDO_MANAGEMENT to AUTO
• E、Set the UNDO_MANAGEMENT parameter to the name of an undotablespace