If the motors on a car continue to take power when the master controller is in the OFF position, what should the train operator do?

If the motors on a car continue to take power when the master controller is in the OFF position, applying the brakes in an emergency is the correct action to take. This situation indicates a serious malfunction since the motors should not be receiving power with the controller in the OFF position. By applying the brakes, the train operator is taking immediate action to ensure the safety of the train crew and passengers, reducing the risk of uncontrolled movement.

In scenarios where there is an unexpected or uncontrollable operation of the train, emergency procedures are crucial to prevent accidents or hazardous situations. This proactive step can help to stop the train and regain control, allowing time for further assessments or corrective actions.

The other options, while possibly relevant in different contexts, do not address the immediate safety concern posed by the malfunction. Calling for assistance could be a subsequent step after ensuring control of the train. Restarting the controller without addressing the power issue could exacerbate the situation. Checking the power source might be necessary later, but ensuring the train does not move is the immediate priority.