You have two servers that run Windows Server 2008 named Server1 and Server2. You install Windows Server Update Services （WSUS） on both servers.You need to configure WSUS on Server1 to receive updates from Server2. What should you do on Server1？（）

• A、Configure a proxy server.
• B、Configure an upstream server.
• C、Create a new replica group.
• D、Create a new computer group.