Your network contains an Active Directory domain. The domain contains several domain  controllers.   All domain controllers run Windows Server 2008 R2.   You need to restore the Default Domain Controllers Policy Group Policy object （GPO） to the  Windows Server 2008 R2 default settings.     What should you do（）

• A、Run dcgpofix.exe /target：dc.
• B、Run dcgpofix.exe /target：domain.
• C、Delete the link for the Default Domain Controllers Policy， and then run gpupdate.exe /sync.  
• D、Delete the link for the Default Domain Controllers Policy， and then run gpupdate.exe /force.