What action is most effective for saving fuel?

What action is most effective for saving fuel?
A)Turn off the engine whenever the vehicle is stationary, even during momentary stops.
B)Inflate the tyres to a pressure lower than that recommended by the manufacturer.
C)Not to overload the vehicle.Correct
A good measure for saving fuel is not to overload the vehicle. Increased mass will cause the vehicle to consume more fuel.
We must avoid carrying more weight than necessary and place the load correctly, as these factors also affect fuel consumption (use the roof rack only when you have no other option, as it increases consumption, even without a load).