How should a gatekeeper, the Cisco CallManager, and an IP-videoconferencing MCU be configured so that calls can be properly routed when an MCU dials out to the E.164 address of an endpoint?

A.
The MCU must register with the Cisco CallManager as an alternate gatekeeper.

B.
The MCU must register with the gatekeeper, and the Cisco CallManager must register with the MCU with a H.225 trunk.

C.
The MCU must register with a H.225 gatekeeper-controlled trunk to the gatekeeper, and the Cisco CallManager must be registered with the gatekeeper.

D.
The MCU must register with the gatekeeper, and the Cisco CallManager must register to the gatekeeper with a H.225 gatekeeper-controlled trunk.