A capacitor motor may have which type of switch that could prevent starting?

A centrifugal switch is correctly identified as a component that could prevent a capacitor motor from starting. This switch is generally used in capacitor start motors and has a specific function related to the motor's operation. As the motor spins up to a specific speed, the centrifugal switch activates, disconnecting the start capacitor and possibly the start winding as well.

If the centrifugal switch fails to operate correctly—either not closing when it should or failing to open after reaching the requisite speed—the motor may not start properly. This can lead to situations where the motor is either stuck trying to start or continuously trying without being able to engage properly.

The other options represent types of switches or devices that can serve different functions in electrical circuits or motor control but do not have the same specific operational role in relation to the starting mechanism of a capacitor motor. Thus, the centrifugal switch stands out as the appropriate choice for this scenario.