You install a new Exchange Server 2010 server.You need to ensure that users can connect from the Internet to the server by using Exchange ActiveSync.What should you do on the Exchange server？（）

• A、Modify the internal URL for the Microsoft-Server-ActiveSync virtual directory.
• B、Modify the external URL for the Microsoft-Server-ActiveSync virtual directory.
• C、Enable Anonymous Authentication for the Microsoft-Server-ActiveSync virtual directory.
• D、Enable Windows Integrated Authentication for the Microsoft-Server-ActiveSync virtual directory.