Your network is configured as shown in the exhibit. You deploy two Lync Server 2010 Front End Servers in the companys data center and you enable Enterprise Voice. You need to recommend a voice strategy for the branch offices that meets the following requirements: If a single WAN link fails, users in all offices must be able to call each other.The number of Lync Server 2010 servers in the branch offices must be minimized. What should you include in the recommendation?

A.
In Branch1, deploy a Survivable Branch Appliance (SBA). In Branch2, deploy a PSTN gateway.

B.
In Branch1, deploy a Lync Server 2010 Mediation Server. In Branch2, deploy a PSTN gateway.

C.
In Branch1, deploy a Lync Server 2010 Mediation Server. In Branch2, deploy a Lync Server 2010 Mediation Server.

D.
In Branch1, deploy a Survivable Branch Appliance (SBA). In Branch2, deploy a Lync Server 2010 Mediation Server.