A.The online redo log files and online data files are opened.
B.All the online data file headers are checked for consistency.
C.Instance recovery is performed before opening the database.
D.The path and existence of all the log file members are checked

A.When the data file of the undo tablespace is autoextensible
B.When there are more than one undo tablespaces available in the database
C.When the undo tablespace is of a fixed size and retention guarantee is not enabled
D.When the undo tablespace is autoextensible and retention guarantee is not enabled