Your network contains two Active Directory forests named contoso.com and litwareinc.com. A two- way forest trusts exists between the forest. Selective
authentication is enabled on the trust.
The contoso.com forest contains a server named Server1.
You need to ensure that users in litwareinc.com can access resources on Server1.
What should you do?
A. Install Active Directory Rights Management Services on a domain controller in contoso.com.
B. Modify the permission on the Server1 computer account.
C. Install Active Directory Rights Management Services on a domain controller in litwareinc.com.
D. Configure SID filtering on the trust.
Selective authentication between forests
If you decide to set selective authentication on an incoming forest trust, you need to manually assign permissions on each computer in the domain as well as the
resources to which you want users in the second forest to have access. To do this, set a control access right Allowed to authenticate on the computer object that
hosts the resource in Active Directory Users and Computers in the second forest. Then, allow user or group access to the particular resources you want to share.
Reference: Accessing resources across forests