You define an alert to be raised when the USERS tablespace usage has reached 80% of the total space. Which area would you refer to， in order to confirm that the alert has been raised due the event？（）

A.Set the UNDO_RETENTION parameter to 900 or more.
B.Create an initial undo segment in the undo tablespace.
C.Enable the retention guarantee for the undo tablespace.
D.Set the UNDO_TABLESPACE parameter to UNDO_TBS1.
E.Set the UNDO_MANAGEMENT initialization parameter to AUTO.

A.MTTR Advisor would be disabled.
B.Redo Log Advisor would be disabled.
C.Automatic tuning of checkpoint would be disabled.
D.Checkpoint information would not be written to the alert log file.

A.The database would open normally.
B.The database would not open， and it would stop at mount stage.
C.The database would open after automatically performing instance recovery.
D.The database would not open， and you have to perform database recovery to open it.