What is the relationship between a Region and a Location?

What is the relationship between a Region and a Location?

A.
The codec parameter configured in the Region is only used between Regions and Location bandwidth is only used between Locations.

B.
The Region codec parameter is used between a Region and its configured Locations.

C.
The Region codec parameter is combined with Location bandwidth when communicating with other Regions.

D.
The Region setting for a Location sets the number of audio and video calls that Location can support.