What is required to implement Auto Image Replication?

A.
BasicDisk or AdvancedDisk storage units and at least one Master Server

B.
OST-compliant appliances or MSDP and at least one Master Server

C.
OST-compliant appliances or MSDP and at least two Master Servers

D.
BasicDisk or AdvancedDisk storage units and at least two Master Servers

Explanation:
http://www.settlersoman.com/how-to-configure-netbackup-auto-image-replication-air/