What should a driver of a commercial vehicle do before going down a steep grade?

When preparing to descend a steep grade, shifting to a lower gear is crucial for controlling the vehicle's speed and preventing brake overheating. By downshifting, the driver uses engine compression to help slow the vehicle, reducing reliance on the brakes. This practice enhances safety, as it allows for better control while managing the significant gravitational forces acting on the vehicle during the descent.

The other choices lack safety considerations appropriate for navigating steep grades. For example, accelerating to maintain speed could lead to losing control on a decline, while changing lanes is irrelevant to the specific task of managing speed on a slope. Engaging cruise control can also be dangerous, as it might increase speed uncontrollably due to the incline, making it harder for the driver to respond effectively to the descent.