Question

Which car has the highest efficiency? (Assume all cars have the same mass.)
Responses

a car that traveled 20 kilometers on 2 liters of gas
a car that traveled 25 kilometers on 1 liter of gas
a car that traveled 20 kilometers on 1 liter of gas
a car that traveled 25 kilometers on 2 liters of gas

The car that traveled 25 kilometers on 1 liter of gas has the highest efficiency.