Your network consists of a single Active Directory domain. All domain controllers run Windows Server  2003.   You upgrade all domain controllers to Windows Server 2008 R2.   You need to ensure that the Sysvol share replicates by using DFS Replication (DFS-R).  What should you do（） 

• A、From the command prompt， run netdom /reset.
• B、From the command prompt， run dfsutil /addroot：sysvol.
• C、Raise the functional level of the domain to Windows Server 2008 R2.
• D、From the command prompt， run dcpromo /unattend：unattendfile.xml.