You are presented with the question "Decreasing what during travel likely conserves fuel?" and the following answer choices: 
- the energy of the car
 - air mass over Earth's surface
 - the amount of cars used
 - the size of the wheels
 - the amount of water used
 - kinetic energy
 - preventing heat transfer
 - energy usage

Now knowing that carpooling decreases the amount of cars used to travel to a place and arrange carpools to conserve fuel, choose the best answer.


 

   the amount of cars used      