The chart below shows four identical wagons loaded with different amounts of bricks.
 Wagon w
 Wagon X
 Wagon Y
 Wagon 2
 two pounds of bricks
 three pounds of bricks
 four pounds of bricks 
 five pounds of bricks
 It the same amount of effort is applied to all four identical wagons, why would Wagon W move farthest?
 A It has the least amount of mass, affecting its motion.
 B. It has the least amount of speed, affecting its motion.
 C. It has the greatest amount of gravity, affecting its motion.
 D. It has the greatest amount of friction, affecting its motion.