Goal 1.2 includes 'action in case of failure' of safety controls. If a retarder warning appears on a descent, what is the professional response?

1. Ignore it because ESP will hold the vehicle
2. Switch off ABS to restore the retarder
3. Treat the descent as a degraded-control situation: reduce speed early, use gear and remaining brakes within their limits, and stop in a safe place if control cannot be maintained
4. Increase speed to shorten time on the grade