What reflects the condition of the switch in operational signaling systems?

The switch detector light is a crucial component in operational signaling systems because it provides a clear and immediate visual indication of the switch's current position and operational status. When the switch is in the required position for the safe operation of trains, the light typically shows green; if the switch is not correctly aligned, the light will display red. This visual cue allows operators to quickly assess whether the switch is correctly set, thereby enhancing safety and efficiency in train operations.

The other options, while they may contribute to the overall signaling and safety framework, do not provide as direct an indication of the switch's condition. Lever locking refers to the mechanical security of the lever position, but does not convey real-time status. The call-on button is used to signal or request permission to proceed but does not indicate the operational state of the switch. Lever color coding aids in identifying the purpose or status of specific levers but lacks the immediate feedback provided by the switch detector light regarding the actual condition of the switch.