Which of the following server clusters offers increased availability， performance， and scalability？（）

A.A collection of disks presented as storage to a single server through an existing network.
B.A collection of disks presented as storage to a single server through directly attached technologies.
C.A collection of disks presented as storage to multiple servers through dedicated channels.
D.A collection of disks presented as storage to multiple servers through an existing network.

A. Cold site
B. Warm site
C. GFS
D. Hot site