You need to access resources located in another forest. Which should you create?

A child domain is a domain within the same Active Directory forest and does not provide access to resources in a separate forest.

Distribution groups are used for email distribution and do not provide functionality for cross-forest resource access.

A trust relationship allows users and groups in one Active Directory forest to be authenticated and authorized to access resources in another Active Directory forest. This establishes a secure communication path and grants cross-forest access permissions.

An Organizational Unit (OU) is a container within an Active Directory domain used for organizing objects and delegating administration, not for facilitating access to resources in another forest.