The system automatically disables write caching when _________. (Choose the best answer.)

A.
a disk pool is being expanded by adding a drive

B.
a failed disk drive has put a volume group into a degraded state

C.
there is a failed controller on the system, so that cache mirroring is unavailable

D.
the system detects a small percentage of cache hits over a 10-minute timeframe

E.
more than 4 unique host identifiers are trying to access the same volume