An administrator must configure a server that prioritizes data availability.

The correct answer is D. RAID 10 (also called RAID 1+0).

According to CompTIA A+ Core 1 220-1201 objectives under Storage:

RAID 10 combines the mirroring of RAID 1 with the striping of RAID 0. This provides both high data availability (because each drive has a mirror) and improved performance (because data is striped across multiple disks).

RAID 10 requires a minimum of four drives and is suitable for servers that handle high I/O workloads while maintaining redundancy.

Why the other options are incorrect:

A. RAID 1: Provides mirroring for redundancy but does not improve performance as effectively as RAID 10.

B. RAID 0: Provides striping for performance but has no redundancy; a single drive failure results in data loss.

C. RAID 5: Provides parity and can tolerate one drive failure with decent read performance, but write performance is lower than RAID 10 and rebuilds can impact system performance under heavy load.