A.A text copy of the control file.
B.A binary copy of the control file.
C.A file containing a SQL statement which will re-create the database.
D.A file containing a SQL statement which will re-create the control file.

A.A checkpoint defines the highest system change number （SCN）.
B.All redo entries higher or at the SCN are known to be written to the data files.
C.Only the redo records containing SCNs higher then the checkpoint need to be applied during recovery.
D.The LOG_CHECKPOINT_INTERVAL initialization parameter specifies the amount of time between incremental checkpoints.