How should directory number of the phone and the Cisco Telepresence endpoint be configured in the Cisco Unified CallManager?

A.
As a shared line where the codec and IP Phone share the same directory number

B.
As a single line for the codec and a single line for the phone using the same directory number

C.
As an overlay line using the same directory number

D.
As a single line for the phone and it only has a directory phone number. The codec uses the IP address of the phone