The proper method of braking when going down long and/or steep grades is to brake until your speed is about ___ miles per hour below your "safe" speed and then release your brakes.

When descending long and/or steep grades, managing your speed is crucial for safety. The correct method involves braking to reduce your speed to a certain level below your "safe" speed, then releasing the brakes to avoid overheating. Braking intermittently helps maintain control and prevents brake fade, which can occur if brakes are applied continuously for prolonged periods.

Braking until you reach about 5 miles per hour below your "safe" speed allows for a sufficient cushion, providing better vehicle control while still ensuring that your brakes do not overheat. This technique helps keep the vehicle manageable while descending, as it allows you to use engine braking in conjunction with the brakes, thereby optimizing brake performance and safety.

The other options suggest larger speed reductions, which might seem safer at a glance but could lead to unnecessary brake strain or unwanted changes in vehicle dynamics during the descent.