You are the administrator of ExamSheet.net's network.   ExamSheet.net upgrades its network to 100 Mbps. All Windows 2000 Professional computers have recently upgraded with new 10/100 Mbps network adapters. All computers have been configured with TCP/IP protocol settings so that IP and DNS settings are obtained automatically. A user has reported that he cannot access the network. You view the network adapters node in Device Manager as shown in the Device Manager window. See exhibit. You want this computer to communicate on the network using the least amount of administrative effort. What should you do?（）

• A、Configure IP address settings manually
• B、Replace the network adapter. Reinstall the network adapter driver
• C、Enable the network adapter.
• D、Enable IEEE 802.1x authentication.