Your company has an Active Directory domain. The company has two domain controllers named DC1   and DC2. DC1 holds the schema master role.    DC1 fails. You log on to Active Directory by using the administrator account. You are not able to transfer  the schema master role.    You need to ensure that DC2 holds the schema master role.  What should you do（）

• A、Register the Schmmgmt.dll. Start the Active Directory Schema snap-in.
• B、Configure DC2 as a bridgehead server.
• C、On DC2， seize the schema master role.
• D、Log off and log on again to Active Directory by using an account that is a member of the Schema  Admins group. Start the Active Directory Schema snap-in.