After executing the command alter diskgroup disk group2 drop disk dg2a； you issue the following command from the ASM instance：   Select group_number， count（*） from v$asm_operation；   What is the implication if the query against V$ASM_OPERATION returns zero rows？（）  

• 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.