What is the benefit of deploying a gatekeeper in an H.323 IP telephony network?

What is the benefit of deploying a gatekeeper in an H.323 IP telephony network?

A.
provides spatial redundancy through the use of HSRP

B.
provides load balancing via GUP when alternate gatekeepers are deployed

C.
reduces configuration complexity by centralizing the dial plan

D.
increases redundancy by allowing each gateway to maintain a copy of the dial plan