An organization plans to migrate to Office 365. You use Azure AD Connect.Several users will not migrate to Office 365. You must exclude these users from synchronization. All users must continue to authenticate against the on-premises Active Directory.
You need to synchronize the remaining users.
Which three actions should you perform to ensure users excluded from migration are not synchornized?
Each correct answer presents part of the solution.

A.
Run the Windows PowerShell command Set-MsolDirSyncEnabled -EnableDirSync $false

B.
Perform a full synchronization.

C.
Populate an attribute for each user account.

D.
Configure the connection filter.

E.
Disable the user accounts in Active Directory.

Explanation:
http://www.proexchange.be/blogs/office365/archive/2011/07/28/modify-dirsync-to-not-sync-all-usersto-office-365.aspx