Your network contains an Active Directory forest named contoso.com. The contoso.com domain
only contains domain controllers that run Windows Server 2012 R2.
The forest contains a child domain named child.contoso.com. The child.contoso.com domain only
contains domain controllers that run Windows Server 2008 R2. The child.contoso.com domain
contains a member server named Server1 that runs Windows Server 2012 R2.
You have access to four administrative user accounts in the forest. The administrative user accounts
are configured as shown in the following table.

You need to ensure that you can add a domain controller that runs Windows Server 2012 R2 to the
child.contoso.com domain.
Which account should you use to run adprep.exe?

A.
Admin1

B.
Admin2

C.
Admin3

D.
Admin4

Explanation:
Adprep.exe performs operations that must be completed on the domain controllers that run in an
existing Active Directory environment before you can add a domain controller that runs that version
of Windows Server.
Preparing to run adprep /domainprep (see step 2 below).
To help ensure that the adprep /domainprep command runs successfully, complete these steps
before you run the command on the infrastructure operations master role holder in each domain:
Make sure that the schema updates that adprep /forestprep performs replicated throughout the
forest or that they at least replicated to the infrastructure master for the domain where you plan to
run adprep /domainprep.
Make sure that you can log on to the infrastructure master with an account that is a member of the
Domain Admins group.
Verify that the domain functional level is appropriate.

Running Adprep.exe
http://technet.microsoft.com/en-us/library/dd464018(v=ws.10).aspx