A corporate environment includes an on-premise implementation of Exchange Server 2010 SP1. The company intends to use a cloud-based Exchange Server 2010 SP1 provider to provide email service for the Sales team. All other mailboxes will remain in the on-premise environment. You have the following requirements:

* Ensure that all users can access mailboxes by using corporate Active Directory Domain Services (AD DS) credentials.
* Ensure that all users can access a global address list (GAL) that includes all email addresses. You need to recommend a coexistence solution that meets the requirements.

Which two actions should you recommend? (Each correct answer presents part of the solution. Choose two.)

A.
Implement Active Directory Federation Services 2.0 (AD FS 2.0).

B.
Implement Microsoft Forefront Unified Access Gateway 2010 (UAG 2010).

C.
Synchronize AD DS from the on-premise environment to the cloud-based environment.

D.
Synchronize AD DS from the cloud-based environment to the on-premise environment.