You are the network administrator for TestKing, which employs 500 users. The network consists of a single Active Directory domain named All network servers run Windows Server 2003, and all client computers run Windows XP Professional. You install Terminal Services on three servers TestKing1, TestKing2, and TestKing3. Initially, users can successfully connect to all three terminal servers by using Remote Desktop connections. Months later, users begin reporting that they can no longer connect to any of the terminal servers by using Remote Desktop connections. How should you solve this problem?（）

• A、On each terminal server, change the licensing mode form Per Server to Per Seat.
• B、Add additional Microsoft Windows licenses to the Site License server for the domain.
• C、Configure and activate an Enterprise license server.
• D、On each terminal server, change the licensing mode from Per Device to Per User.