You are employed as the Exchange administrator at Company.com.The Company.com network contains Exchange Server 2007 as well as Exchange Server 2010 Hub Transport server.You are responsible for managing the Exchange network for Company.com.You are in the process of creating a moderated distribution group named Research.A Company.com user named Rory Allen is assigned as the moderator of Research.During the course of the week Rory Allen informs you that certain e-mail messages delivered to members of the Research group does not have his approval.You need to make sure that only approved e-mail messages by Rory Allen are delivered to members of the Research group.What should you do？（）

• A、This can be achieved by forcing a replication between the domain controllers.
• B、This can be achieved by recreating Research as a dynamic distribution group.
• C、This can be achieved by changing the expansion server for the Research group.
• D、This can be achieved by restarting the MSExchangeTransport Service.