You deploy a new Active Directory forest named contoso.com. All domain controllers run Windows Server 2012 and are DNS servers. The contoso.com DNS zone is Active Directory-integrated. You plan to deploy a new tree in the forest named adatum.com. All domain controllers in adatum.com will be DNS servers. All computers in adatum.com will use the domain controllers in adatum.com as DNS servers. You need to recommend a solution to ensure that users in contoso.com can resolve the names of the domain controllers in adatum.com. What should you include in the recommendation?
A. changes to the replication scope of _msdcs.adatum.com
B. changes to the replication scope of contoso.com
C. changes to the replication scope of adatum.com
D. a zone delegation for _msdcs.contoso.com