What is a prerequisite of AAR deployment?

What is a prerequisite of AAR deployment?

A.
You must have a single distributed call processing deployment.

B.
Calls must be manually rerouted through the PSTN or other networks when Cisco Unified Communications Manager blocks a call due to insufficient location
bandwidth.

C.
Calls must be automatically rerouted through the PSTN or other networks when Cisco Unified Communications Manager blocks a call due to insufficient location
bandwidth.

D.
Clustering must be implemented over the WAN.

E.
You must have a centralized call processing deployment.