Which car has the greatest efficiency?

Question

A. A 900 kg car that travels 20km per liter of fuel
B. A 1,200 kg car that travels 15 km per liter of fuel
C. A 1,200 kg car that travels 20km per liter of fuel
D. A 900 kg car that travels 15 km per liter of fuel

Answer 1

C. A 1,200 kg car that travels 20km per liter of fuel