You have a domain controller named DC1 that runs Windows Server 2008 R2. DC1 is configured as a   DNS server for contoso.com.   You install the DNS Server server role on a member server named Server1 and then you create a  standard secondary zone for contoso.com. You configure DC1 as the master server for the zone.  You need to ensure that Server1 receives zone updates from DC1.   What should you do（）

• A、On Server1， add a conditional forwarder.
• B、On DC1， modify the permissions of contoso.com zone.
• C、On DC1， modify the zone transfer settings for the contoso.com zone.
• D、Add the Server1 computer account to the DNSUpdateProxy group.