What are two potential causes for this?

When attempting to place a datastore in Maintenance Mode, the task remains at 1%.
What are two potential causes for this? (Choose two.)

A.
Storage DRS is disabled on one or more virtual machine(s) disk(s).

B.
Storage DRS rules prevent migration recommendations for the disk.

C.
Storage DRS datastores have insufficient space to accommodate failover.

D.
Storage DRS provisioning network has been limited with I/O control policies.