Which two other objects should you have created first?

You are preparing to configure your VoIP Domain Gatekeeper object. Which two other objects should you have created first?

A.
An object to represent the IP phone network, AND an object to represent the host on which the proxy is installed

B.
An object to represent the PSTN phone network, AND an object to represent the IP phone network

C.
An object to represent the IP phone network, AND an object to represent the host on which the gatekeeper is installed

D.
An object to represent the Q.931 service origination host, AND an object to represent the H.245 termination host

E.
An object to represent the call manager, AND an object to represent the host on which the transmission router is installed