A corporate environment includes an on-premise deployment of Exchange Server 2010 SP1. Client computers run Microsoft Outlook 2010. Contractors use a cloud-based Exchange Server 2010 SP1 service and have email accounts on the contractors.contoso.com domain. Employees cannot view calendar availability information for contractors from their client computers. You need to recommend the first step in sharing calendar availability information between employees and contractors.

What should you recommend?

A.
Create a forest trust.

B.
Create a sharing policy.

C.
Create a federation trust.

D.
Create an organization relationship.