You are a messaging professional. Your company plans to upgrade from a Microsoft Exchange Server 2003 messaging system to a Microsoft Exchange Server 2007 messaging system.

Your company has implemented a Microsoft Active Directory forest that contains a single domain. All servers in the domain run Microsoft Windows Server 2003 R2 x86 Standard Edition. The domain functional level and the forest functional level are left at their default.

You need to ensure that your messaging environment is ready to add the first Exchange Server 2007 server.

What should you do to ensure that your messaging environment is ready to add the first Exchange Server 2007 server?

A.
Install Service Pack 1 or later version on your Exchange Server 2003 server.

B.
Upgrade all the domain controllers to Windows Server 2003 R2 x86 Enterprise Edition.

C.
Upgrade all the domain controllers to Windows Server 2003 R2 64-bit Standard Edition.

D.
Raise your domain functional level to at least Microsoft Windows 2000 Domain in Native mode.