When an Employee determines that a switch or derail is defective, the employee must?

Answer: A — Not operate the device

Defective switching equipment is a safety hazard because it may not hold its position or could move unexpectedly, potentially causing a derailment or misrouting. The immediate action is to not operate the device, removing any chance of unintended movement. After that, you should notify a supervisor so the issue can be inspected and repaired. Others actions, like operating cautiously or rerouting, could still allow a dangerous situation to develop or mask the fault, so the safest first step is not to operate the device.