You have a single Active Directory directory service domain with three domain controllers named  DC1， DC2， and DC3. All FSMO roles are held on DC1. All domain controllers are global catalog servers.   Several users are experiencing logon times that are longer than normal. All users are authenticating with   DC1 and DC3. The DC2 logs display error messages indicating that the Active Directory database  partition is out of free space. You need to ensure that Active Directory is accessible on DC2. You add a  500-GB hard disk to DC2， back up the system state data， and restart DC2 in Directory Services Restore  Mode.  What should you do next？（）

• A、 Use Windows Explorer to move ntds.dit to the new hard disk.
• B、 Use the Ntdsutil tool to move ntds.dit to the new hard disk.
• C、 Create a new application directory partition.
• D、 Perform an authoritative restore of Active Directory.