You need to ensure that DC2 can resolve DNS queries for ad.contoso.com in the event that a WAN link fails

Your company, Contoso, Ltd., has a main office and a branch office. The offices are
connected by a WAN link. Contoso has an Active Directory forest that contains a single
domain named ad.contoso.com.
The ad.contoso.com domain contains one domain controller named DC1 that is located in
the main office. DC1 is configured as a DNS server for the ad.contoso.com DNS zone. This
zone is configured as a standard primary zone.
You install a new domain controller named DC2 in the branch office. You install DNS on
DC2.
You need to ensure that DC2 can resolve DNS queries for ad.contoso.com in the event that
a WAN link fails. The solution must prevent DC2 from updating records in ad.contoso.com.
What should you do?

A.
Configure the DNS server on DC2 to forward requests to DC1.

B.
Convert the ad.contoso.com zone on DC1 to an Active Directory-integrated zone.

C.
Create a new secondary zone named ad.contoso.com on DC2.

D.
Create a new stub zone named ad.contoso.com on DC2.

Explanation: