You work as the enterprise exchange administrator at Xxx .Xxx is using Microsoft Exchange Server 2010 as their messaging solution.How can you to configure Outlook Web App （OWA） to block Xxx employees from changing passwords？（）

• A、You must use IP Block list.
• B、You must change the properties of the OWA virtual directory.
• C、You must use an Outlook Web App Mailbox policy.
• D、You must set up recipient filtering.