To slow down the apparatus for a stop, a driver using a manual transmission should?

Shifting into a lower gear is the correct approach for slowing down an apparatus with a manual transmission. When a driver downshifts, the engine RPM increases, which allows the engine to provide additional braking force through engine compression. This process, known as engine braking, can significantly enhance control while reducing speed and helps to prevent wear on the brake components by allowing the vehicle to decelerate without relying solely on the brakes.

In contrast, shifting into a higher gear would cause the vehicle to accelerate rather than slow down, which is not appropriate when the goal is to stop or slow the apparatus efficiently. Engaging the emergency brake is usually not advisable as the primary method of slowing down, especially in a large vehicle like an aerial ladder, as it can cause the vehicle to skid or lose control. Coasting without shifting would not utilize engine braking effects and could lead to increased stopping distances, making it less effective for slowing down safely.