You need to configure bi-directional name resolution between the two forests

Your network contains two Active Directory forests named contoso.com and corp.contoso.com.

User1 is a member of the DnsAdmins domain local group in contoso.com.
User1 attempts to create a conditional forwarder to corp.contoso.com but receive an error message
shown in the exhibit. (Click the Exhibit button.)

You need to configure bi-directional name resolution between the two forests.
What should you do first?

A.
Add User1 to the DnsUpdateProxy group.

B.
Configure the zone to be Active Directory-integrated.

C.
Enable the Advanced view from DNS Manager.

D.
Run the New Delegation Wizard.

Explanation:
The zone must be Active Directory-integrated.