A GIF Animation
Depress mouse to view answer. If you inspect each car individually, you will more likely notice that only the green and the blue cars accelerate. The red car moves with a constant speed, covering the same distance in each second of the animation. The green and the blue cars are speeding up, thus covering an increasing distance in each second of the animation.
Depress mouse to view answer. The blue car has a greater acceleration. It is changing its velocity at a more drastic rate.
Depress mouse to view answer. The red car is moving with a constant velocity and must correspond to object B which has a constant slope. The green and blue cars have a changing velocity and must correspond to lines with a changing slopes - objects A and C. The green car is object C which has a more gradually changing slope than object A (blue car).