The distance, y, in miles, traveled by a car for a certain amount of time, x, in hours, is shown in the graph below: A graph titled Motion of a Car is shown with Time in hours labeled on x-axis and Distance from Starting Point in miles labeled on y-axis. The scale on the x-axis shows the numbers 1, 2, 3, 4, 5, 6, and the scale on the y-axis shows the numbers 0, 12, 24, 36, 48, 60, 72. There are three straight lines in the graph. The first line joins ordered pair 0, 0 with 1, 12. The second straight line joins 1,12 and 2,12 and the third straight line joins ordered pair 2,12 with the ordered pair 5,36. Which of the following best describes the motion of the car shown?