You have a Lync Server 2013 infrastructure that contains three Enterprise Edition Front End pools named Pool1, Pool2, and Pool3. Pool1 and Pool2 are located in a
data center in Montreal.
Pool3 is located in a data center in Seattle.
You need to recommend changes to the Lync Server 2013 infrastructure to ensure that all users can access Lync services if a data center fails.
What should you recommend?

A.
Pair Pool1 and Pool3. Pair Pool2 and Pool3.

B.
Create a new pool named Pool4 in the Seattle data center. Pair Pool2 and Pool4. Pair Pool1 and Pool3.

C.
Create a new pool named Pool4 in the Seattle data center. Pair Pool3 and Pool4. Pair Pool1 and Pool2.

D.
Pair Pool1 and Pool2. Pair Pool2 and Pool3.

Explanation:
http://technet.microsoft.com/en-us/library/jj204697.aspx