Why is there a need for at least two simultaneous volume mounts per reclamation process and two drives if the device type is not FILE?

Why is there a need for at least two simultaneous volume mounts per reclamation process and two drives if the device type is not FILE?
A . To allow the multiplexing of data to the volumes while running reclamation.
B . One of the drives is for the data and the other one is for the metadata.
C . At least two drives are used to make sure there is no data loss during reclamation.
D . One of the drives is for the input volume and the other one is for the output volume.

Answer: A