A driver is descending a wet hill in a vehicle fitted with a retarder. What is the best professional use of the retarder?

1. Use it smoothly and appropriately as part of speed control, while maintaining traction and following the vehicle guidance
2. Apply it abruptly at the last moment on every bend
3. Use it to compensate for following too closely
4. Rely on it so the service brakes and road speed no longer matter