Which situation is the best represented by the graph?
a).an airplane starts slowly on the runway, and then quickly takes off before finding a nice cruising speed
b).a swimmer starts at a steady pace, slows down to a stop, and then starts up swimming again, but slower pace than when she first start.
c).after a ball is thrown into the air, it falls back to the ground and bounces
d).a car starts on flat ground and drives quickly up a hill, and then its keeps driving.