Your company has a main office and a branch office. The company has a single-domain Active  Directory forest.   The main office has two domain controllers named DC1 and DC2 that run Windows Server 2008  R2. The branch office has a Windows Server 2008 R2 read-only domain controller （RODC）named DC3. All domain controllers hold the DNS Server server role and are configured as Active  Directory- integrated zones. The DNS zones only allow secure updates.     You need to enable dynamic DNS updates on DC3.     What should you do（）

• A、Run the Ntdsutil.exe DS Behavior commands on DC3.
• B、Run the Dnscmd.exe /ZoneResetType command on DC3.
• C、Reinstall Active Directory Domain Services on DC3 as a writable domain controller.
• D、Create a custom application directory partition on DC1. Configure the partition to store Active Directory-integrated z