A Customer Requires New MCs for a Large Multi-Site Network

A customer requires new MCs for a large multi-site network with about 600 AP-345s and 30,000 wireless clients. The customer requires redundancy for the MCs with each MC being able to handle the full load in a failover situation. The network should be able to sustain the loss of a controller with stateful failover within seconds. It should be able to undergo software upgrades without downtime. The architect has recommended two 7240XM MCs. The customer points out that 7220 MCs can support enough APs and wonders why the architect recommended the 7240XMs. What should the architect explain?

A) The 7240XMs MCs are required to support the large number of wireless clients in this network.
B) The 7240XMs MCs support 40GbE ports, which are desirable for future proofing.
C) The 7240XMs MCs can support full CPSec tunnels with this number of APs, while the 7220 MCs cannot.
D) The 7240XMs MCs have more advanced clustering and availability capabilities than the 7220s MCs.