Which two statements are true about the UNDROP clause of the ALTER DISKGROUP statement?
A.
It cancels pending drops of disks dropped using the DROP DISKGROUP command.
B.
A disk cannot be undropped as a result of a drop diskgroup.
C.
It automatically unmounts the disks after successfully undropping them.
D.
It is not possible to cancel pending drops of disks dropped using the force option.
Explanation:
The UNDROP DISKS clause of the ALTER DISKGROUP statement cannot be used to restore disks that are
being dropped as the result of a DROP DISKGROUP statement, or for disks that are being dropped using the
FORCE clause.
https://docs.oracle.com/cd/B28359_01/server.111/b31107/asmdiskgrps.htm
B,D