An administrator is troubleshooting a communication issue between two computers on the same Layer 2 switch. Which of the following is the BEST way to determine if the switch is causing the issue?（）

• A、Setup an ACL that allows and logs all IP traffic between the two computers
• B、Configure a spanning tree to check for a loop
• C、Setup a span port on the switch to watch for CRC errors
• D、Connect both computers using a crossover cable