What should you do?

Your company has a main office and a branch office. The main office is located in Amsterdam. The branch office is located in New York. Each office has a data center.
The offices connect to each other by using a high-bandwidth, low-latency wide area network (WAN) link.
You have a Skype for Business Server 2015 infrastructure that contains 5,000 users.
You plan to deploy a persistent chat infrastructure.
You need to ensure that persistent chat rooms remain available if a Persistent Chat Server fails.
What should you do?
A. Create two Persistent Chat Server pools that each contains one active chat server.
B. Create one Persistent Chat Server pool that contains two activechat servers.
C. Create one Persistent Chat Server pool that contains one active chat server and onestandby chat server.
D. Create two Persistent Chat Server pools that each contains one active chat server and one standby chat server.