At what speed does the Deadman's Device become inactive?

The Deadman's Device is designed to ensure the safety of train operations by requiring continuous input or awareness from the operator while the vehicle is in motion. The device typically becomes inactive when the train is stationary or moving at very low speeds, as it is intended to prevent accidental movement when the operator is not in control.

When examining the correct choice, being stationary or under 0.2 km/h indicates a lack of movement sufficient for normal train operation, where the risk of uncontrolled movement is minimal. At this low speed or being stationary, the system recognizes that the operator is not driving the train, and therefore, it deactivates to prevent unnecessary alarms or interventions.

The other choices involve thresholds that either suggest the device remains active at too low of a speed or positions that imply the device should remain engaged regardless of the situation, which does not align with operational practices designed around safety and efficiency in train control systems.