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.

Explanation:
http://technet.microsoft.com/en-us/library/hh875588.aspx
Dcgpofix Recreates the default Group Policy Objects (GPOs) for a domain.
Syntax
DCGPOFix [/ignoreschema] [/target: {Domain | DC | Both}] [/?]
/ignoreschema Ignores the version of the Active Directory® schema when you run this
command. Otherwise, the command only works on the same schema version as the
Windows version in which the command was shipped.
/target {Domain | DC | Both} Specifies which GPO to restore. You can restore the Default
Domain Policy GPO, the Default Domain Controllers GPO, or both.
Examples
Restore the Default Domain Controllers Policy GPO to its original state. You will lose any
changes that you have made to this GPO. dcgpofix /ignoreschema /target:DC