Car A travels east at 15m/s relative to the ground. The driver of Car A throws a ball directly forward so that its speed relative to the car is 10m/s. At the same instant, Car B travels east at 30m/s in the same lane. Which observer will see the ball moving toward the west?
a) The driver of Car A
b) An observer standing on the ground
c) The driver of Car B
d) All three observers see the ball move east