You have an Office 365 environment. Synchronization between the on-premises Active Directory and
Office 365 is enabled.
You need to deactivate directory synchronization.
Which Windows PowerShell cmdlet should you run?

A.
Update-MsolFederatedDomain

B.
Remove-MsolDomain

C.
Remove-MsolFederatedDomain

D.
Set-MsolDirSyncEnabled

Explanation:
The complete command to disable directory Sync is Set-MsolDirSyncEnabled –EnableDirSync $false

http://support.microsoft.com/kb/2619062