Your network contains an Active Directory domain named contoso.com.
All domain controllers run Windows Server 2012 R2. The domain contains two domain controllers.
The domain controllers are configured as shown in the following table.

You configure a user named User1 as a delegated administrator of DC10.
You need to ensure that User1 can log on to DC10 if the network link between the Main site and the Branch site fails.
What should you do?

A.
Add User1 to the Domain Admins group.

B.
On DC10, run ntdsutil and configure the settings in the Roles context.

C.
Run repadmin and specify the /prp parameter.

D.
On DC1, modify the User Rights Assignment in Default Domain Controllers Group Policy object (GPO).

Explanation:
repadmin /prp will allow the password caching of the local administrator to the RODC.
This command lists and modifies the Password Replication Policy (PRP) for read-only domain controllers (RODCs).
https://technet.microsoft.com/en-us/library/cc755310%28v=ws.10%29.aspx