You are unable to telnet to a router at address 203.125.12.1 from a workstation with the IP address 203.125.12.23. You suspect that there is a problem with your protocol stack. Which of the following actions is most likely to confirm your diagnosis?（）

• A、ping 127.0.0.0
• B、ping 203.125.12.1
• C、telnet 127.0.0.1
• D、ping 127.0.0.1
• E、tracert 203.125.12.1