You have a Microsoft Exchange Server 2013 organization that has the following configurations: ✑ The forest functional level if Active Directory is Windows Server 2008 R2. ✑ The domain controllers in Active Directory run 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. Upgrade the Exchange servers to Windows Server 2019.
B. Raise the forest functional level to Windows Server 2012 R2.
C. Upgrade the Exchange servers to Windows Server 2016.
D. Upgrade the domain controllers to Windows Server 2016.