How does the Cisco extended memory technology offer the most memory in a 2 RU server?

A.
It incorporates the memory available in the Cisco UCS B-Series blades.

B.
One virtual DIMM is mapped to four physical DIMMs.

C.
Four physically distinct DIMMs are mapped to a single logical DIMM.

D.
It offers twice the physical DIMMs found in other 2 RU servers.