What is a true statement about downshifting for a long downhill grade?

Answer: B — It allows engine compression and friction to help the brakes slow the vehicle

Downshifting for a long downhill grade is an essential technique that enhances vehicle control and safety. When a driver downshifts, they shift the transmission to a lower gear. This process enables the engine's compression and friction to assist in slowing the vehicle, effectively supplementing the braking system. As the vehicle descends the hill, the engine works to slow it down, reducing reliance solely on brakes, which helps prevent brake overheating and maintains better overall control. This method is particularly useful because long downhill grades can lead to excessive speed if only the brakes are used. By engaging a lower gear through downshifting, drivers can manage their speed more effectively, utilizing both mechanical means and braking systems in tandem. This technique makes driving safer and reduces wear and tear on the brakes, promoting longer brake life and enhancing safety on descents.