A. The disk ABC will be dropped from the disk group. Since you did not issue a rebalance command，the data on that disk will be lost.
B. The command will raise an error indicating that you need to rebalance the disk group to remove the data from that disk prior to dropping the disk.
C. The disk group will be automatically rebalanced during the drop operation. Once the rebalancing is complete，the disk will be dropped.
D. This command will fail because you cannot drop a specific disk in an ASM disk group.
E. The disk drop command will be suspended for a predetermined amount of time，waiting for you to also issue an alter diskgroup rebalance command. Once you have issued the rebalance command，ASM will proceed to rebalance the disk group and then drop the disk.

A. The drop disk operation is still proceeding and you cannot yet run the undrop disks operation.
B. The drop disk operation is complete and you can run the undrop disks command if needed.
C. The drop disk operation is complete and you cannot run the undrop disk command.
D. The query will fail since there is not a V$ASM_OPERATION view available in an ASM instance. 
E. None of the above is true.