Your network contains an Active Directory forest. The forest contains two Active Directory domains named
contoso.com and child.contoso.com. The forest functional level is Windows Server 2003. The functional level of
both domains is Windows Server 2008.
The forest contains three domain controllers. The domain controllers are configured as shown in the following
table.

DC1 and DC2 have the DNS Server server role installed and are authoritative for both contoso.com and
child.contoso.com.
The child.contoso.com domain contains a server named serverl.child.contoso.com that runs Windows Server
2012.
You plan to deploy server1.child.contoso.com as a read-only domain controller (RODC).
You run the adprep.exe /rodcprep command on DC3 andreceive the following error message:

You need to identify what prevents you from successfully running Adprep /rodcprep on DC3.
What should you identify?

A.
The domain functional level of child.contoso.com is set to the wrong level.

B.
DC3 cannot connect to the infrastructure master on DC2.

C.
DC3 cannot connect to the domain naming master onDC1.

D.
The forest functional level is set to the wrong level.