A customer has a system with two 9 GB drives that are hardware mirrored on an Ultra SCSI RAID controller. Using the same size drives, they want to plan for 63 GB of storage space. Which of the following configurations offers the MOST efficient solution?

A.
RAID 5 with twelve additional drives

B.
RAID 5 with seven additional drives

C.
RAID 0+1 with seven additional drives

D.
RAID 0+1 with twelve additional drives