What is the significance of using low gear when driving down a steep grade?

Using low gear when driving down a steep grade is significant because it helps to control the vehicle’s speed safely. When a driver shifts into a lower gear, the engine utilizes engine braking to assist in slowing down the vehicle. This is particularly important on steep inclines, where gravity can cause the car to accelerate uncontrollably. By keeping the vehicle in low gear, the engine's resistance to motion helps maintain a safe speed without solely relying on the brakes. This reduces the risk of brake overheating or failure, ensuring a safer descent.

The other options do not accurately reflect the primary purpose of using low gear on a steep grade. While fuel consumption may vary based on driving conditions, the primary concern when descending a steep hill is speed control, rather than fuel efficiency. Increasing road grip does not pertain to the use of low gear; instead, it relates to the type of tires and road conditions. Therefore, the correct choice highlights the key safety benefit of managing speed while descending.