What must be, at a minimum, the domain functional level of your Active Directory domains before
you can install any Exchange Server 2010 servers?

A.
Windows 2000 mixed

B.
Windows 2000 native

C.
Windows 2000 interim

D.
Windows 2003 native

Explanation:
In each domain that will have Exchange recipients or Exchange Server roles installed, the domain
functional level must be at the Windows 2003 Server native mode or higher.