In a centralized call-processing solution, there are five sites connected through an IP WAN. To optimize the utilization of the IP WAN, CAC needs to be implemented. How should CAC be implemented?

A.
use a gatekeeper to control allocated bandwidth properly

B.
use locations CAC with a single location

C.
use a gatekeeper and Cisco Unified Border Element to provide CAC to sites that use a combination of SIP and MGCP gateways

D.
use a gatekeeper to only control those locations that use H.323 gateways and a Cisco Unified Border Element to control those sites that use MGCP or SIP gateways

E.
use locations CAC with five locations in addition to Hub none