You have an Exchange organization.All servers in the organization have Exchange Server 2010 Service Pack 1 （SP1） installed.The organization contains five Hub Transport servers.All of the Hub Transport servers are listed as source servers for a Send connector to the Internet.  You need to prevent a Hub Transport server named Hubl from sending and receiving e-mail messages from the Internet.The solution must meet the following requirements：  （1）Ensure that Mailbox servers can deliver e-mail messages to Hub1. （2）Ensure that all other Hub Transport servers can deliver e-mail messages to the Internet. What should you do on Hub1？（）

• A、Suspend all message queues.
• B、Stop the Microsoft Exchange Transport service.
• C、Disable all Receive connectors and Send connectors.
• D、Stop the Microsoft Exchange Mail Submission Service.