In which scenario can you reverse the dependent and independent variables and still have a meaningful real-world interpretation of slope?
As the amount of water vapor in the air increases, the rate at which you perspire increases.
As the amount of fuel consumed by a vehicle increases, the distance traveled by the vehicle increases.
As the amount of fertilizer used on a crop increases, the yield of that crop increases.
As the amount of rainfall in a region increases, the groundwater level in the region increases.