Refer to the exhibit.
After the "attach-mirror" command is successfully executed on device "device_VNX0506_CSE__6_1", the command "rebuild-status" shows an ongoing rebuild process on the same device.
What is a possible cause?
A. It is a normal behavior. when attaching a mirror, a rebuild process starts.
B. The device "device_VNX0506_CSE__6_1" has an ongoing rebuild process for a previous failure.
C. The rebuild process is related to a director failure.
D. The device mirror will start only after the rebuild process is completed.