Why is it advised to avoid stopping on a hill while towing a trailer in slippery conditions?

When towing a trailer in slippery conditions, stopping on a hill poses a significant challenge because starting from a complete stop can be extremely difficult. This difficulty arises from the decreased traction available on both the hill and the slick surface. When the vehicle is loaded with a trailer, additional weight combined with the incline can cause the wheels to spin or lose grip entirely when trying to launch from a standstill. Consequently, it becomes increasingly challenging to gain the momentum necessary to safely and effectively crest the hill. Thus, avoiding stops on inclines while towing in such conditions is crucial for maintaining vehicle control and safety.