What must be applied to ensure safety when working on a car?

To ensure safety when working on a car, applying the handbrake or parking brake is essential. Engaging the handbrake secures the vehicle in its position, preventing it from rolling or moving unexpectedly while work is being done. This is especially important when the vehicle is on an incline or if it is being worked on with the engine running.

The handbrake acts as a secondary system that holds the vehicle stationary, additional to the regular braking system. This minimizes the risk of accidents and injuries during maintenance tasks, providing a stable working environment.

While options like emergency stops, neutral gear, and safety cones have their respective uses in vehicle operation and parking scenarios, they do not directly contribute to securing the vehicle when maintenance is underway in the same way the handbrake does.