A corporate environment includes Exchange Server 2003 SP2 and an Active Directory Domain Services (AD DS) forest with two domains. The forest functional level is set to Windows 2000. The domain functional level of Domain1 is set to Windows 2000 mixed. The domain functional level of Domain2 is set to Windows 2000 native.
The AD DS infrastructure is shown in the following table.

Server Domain Operating system
DC1 Domain1 Windows Server 2008
DC2 Domain1 Windows Server 2003 SP1
DC3 Domain2 Windows 2000 Server SP4
DC4 Domain2 Windows 2000 Server SP2

The company plans to transition to Exchange Server 2010 SP1. The new infrastructure must support Windows Server 2003 SP1 domain controllers. You need to recommend a solution for preparing the existing AD DS infrastructure to support Exchange Server 2010 SP1.

Which two actions should you recommend? (Each correct answer presents part of the solutions. Choose two.)

A.
Replace DC2 and DC4 with domain controllers running Windows Server 2008 R2.

B.
Replace DC3 and DC4 with domain controllers running Windows Server 2008.

C.
Raise the functional level of Domain1 to Windows 2000 native. Raise the functional level of the forest to Windows Server 2003.

D.
Raise the functional level of Domain1 to Windows 2008 R2. Raise the functional level of the forest to Windows Server 2008.