Which position of the Selec-Terrain system is used with Hill Descent Control for better control downhill?

The correct choice is the position of the Selec-Terrain system designated for Rock, which enhances the vehicle's capability during downhill descents using Hill Descent Control. This mode is specifically designed to provide maximum traction and stability on rough and steep terrain, making it ideal for navigating rocky surfaces and steep grades.

In Rock mode, the vehicle employs adjusted throttle response and traction control to enhance grip on uneven ground, which is crucial when descending steep inclines. Additionally, this setting allows the vehicle to maintain a slow, controlled speed, preventing the risk of losing traction or rolling over, which can occur on slippery or uneven surfaces.

The other modes, such as Snow, Sand, and Auto, focus on different driving conditions that require varying levels of traction and power distribution. While they are beneficial in their respective contexts, they do not provide the same level of control on rocky terrains as Rock mode does, especially when engaging Hill Descent Control.