Your company plans to migrate from On-Premises Exchange to Exchange Online in Office 365.
You plan to integrate your existing Active Directory Domain Services (AD DS) infrastructure with
Azure AD. You need to ensure that users can log in by using their existing AD DS accounts and
passwords. You need to achieve this goal by using minimal additional systems. Which two actions
should you perform? Each answer presents part of the solution.

A.
Configure Password Sync.

B.
Set up a DirSync Server.

C.
Set up an Active Directory Federation Services Server.

D.
Set up an Active Directory Federation Services Proxy Server.

Explanation:
Directory Sync with Password Sync Scenario’ Applies To: Azure, Office 365, Windows Intune
Password sync is an extension to the Directory Sync Scenario. With directory sync, you can
manage the entire lifecycle of your cloud user and group accounts using your on- premise Active
Directory management tools. When password sync is enabled on your directory sync computer,
your users will be able to sign into Microsoft cloud services, such as Office 365, Dynamics CRM,
and Windows InTune, using the same password as they use when logging into your on-premises
network. When your users change their passwords in your corporate network, those changes are
synchronized to the cloud.
http://technet.microsoft.com/en-us/library/dn441214.aspx