You have a Microsoft Exchange Server 2013 organization that has the following configurations:
The forest functional level of Active Directory is Windows Server 2008 R2
The domain controllers in Active Directory Windows Server 2012 R2
The Exchange servers run Windows Server 2012 Datacenter
You plan to upgrade the organization to Exchange Server 2019.
You need to ensure that the organization meets the minimum supported requirements for the upgrade.
What should you do?
A. Raise the forest functional level to Windows Server 2012 R2
B. Upgrade the domain controllers to Windows Server 2016
C. Upgrade the Exchange servers to Windows Server 2016
D. Upgrade the Exchange servers to Windows Server 2019
