An administrator has four drives, and each drive is 300GB in size. If the administrator applies RAID 6 to four drives, which of the following is the usable capacity of the four drives?

300 GB would only be the usable capacity for a single drive or if three drives were used for parity, which is incorrect for a four-drive RAID 6 configuration.

RAID 6 utilizes two drives for double parity information, providing fault tolerance against two simultaneous drive failures. With four 300GB drives, the capacity of two drives is dedicated to parity, leaving the capacity of the remaining two drives for usable data, resulting in a total usable capacity of (4-2) * 300GB = 600GB.

900 GB would be the usable capacity for a RAID 5 array with four drives (4-1=3 data drives) or for a RAID 6 array with five drives (5-2=3 data drives), not a four-drive RAID 6 array.

1.2 TB (1200 GB) represents the total raw capacity of the four drives, but it does not account for the two drives' capacity consumed by the double parity overhead in a RAID 6 configuration.