how do you ensure the local user accesses their local PSTN given that each remote office is set up with their own local partition and CSS?

From centralized deployment, how do you ensure the local user accesses their local PSTN given that each remote office is set up with their own local partition and CSS?

A.
The local gateway is a member of the local partition.

B.
The remote gateway is a member of the local partition.

C.
The local PSTN Route Pattern is a member of the local partition.

D.
The remote PSTN Route Pattern is a member of the local partition.