Retarders can be used:

• A. Anywhere at any time
• B. Only where permitted by law
• C. Only in daylight
• D. Only on paved roads

Answer: (B)

Retarders are braking devices that help slow a heavy vehicle without using the main service brakes, which reduces brake wear and keeps speeds more controlled on downgrades. Because they can affect noise levels and vehicle behavior, their use is regulated by law. Some roads or areas may prohibit retarder use, or restrict when and where they can be used. So you should operate retarders only where it is permitted by law, and rely on your service brakes as needed based on road conditions and posted rules.