What should you do first?

You are hired as a consultant by ABC Corporation to implement a Windows Server 2008 R2 computer
onto their Windows Server 2003 domain. All of the client machines are Windows 7.
You install Windows Server 2008 R2 onto a new computer and join that computer to the Windows 2003 domain.
You want to upgrade the Windows Server 2008 R2 to a domain controller.
What should you do first?
A. On the new server, run adprep /domainprep.
B. On the new server, run adprep /forestprep.
C. On a Windows Server 2003 domain controller, run adprep /domainprep.
D. On a Windows Server 2003 domain controller, run adprep /forestprep.