You have upgraded the forest root domain so that it now has Windows Server 2008 R2 domain controllers. You now plan to upgrade a child domain in the same forest. Assuming that no domain controller in the forest hosts more than one flexible single master operations (FSMO) role, on which domain controller in the child domain should you run the adprep /domainprep /gpprep command?

A. Domain controller hosting the PDC emulator role B. Domain controller hosting the schema master role C. Domain controller hosting the RID master role D. Domain controller hosting the infrastructure master role E. Domain controller hosting the domain naming master role