Your company has two domain controllers named DC1 and DC2. DC1 host all domain and forest operations master roles.  DC1 fails.  You need to rebuild DC1 by reinstalling the operating system. Youn also need to rollback all operations master roles to their original state. You perform a metadate cleanup and remove all references of DC1. Which three actions should you perform next（）

• A、A
• B、B
• C、C
• D、D
• E、E
• F、F