In order to troubleshoot an issue with the Testking frame relay network, you log into a remote router via a telnet session and issue the command "debug frame-relay lmi". After a long wait, you fail to see any output. What could be the cause of this problem?（）
- A The IP addresses are configured incorrectly.
- B Frame Relay LMI messages not displayed in real time.
- C The administrator must issue the enable frame-relay lmi debug command.
- D The administrator must issue the terminal monitor command.
- E Debug messages can only be received once through the console port.
- F The administrator must issue the show frame-relay lmi vty 0 4 command