You have a Skype for Business Server 2015 infrastructure that contains an Enterprise Edition front end pool. You plan to

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You have a Skype for Business Server 2015 infrastructure that contains an Enterprise Edition front end pool.
You plan to add the following servers and roles to the existing infrastructure:
✑ Edge Server
✑ Archiving role
✑ Monitoring role
✑ Persistent Chat Server
You need to add Microsoft SQL Server servers to the existing Skype for Business Server 2015 infrastructure. The solution must not use the existing SQL Server
Back End Server.
What is the minimum number of SQL Server servers that you should add?

A. 1
B. 2
C. 3
D. 4