A hot air balloon is rising at a constant rate. The relationship between its height above the ground and the time since it left the ground is shown in the following graph. Which statements about the graph are true? Choose all answers that apply: A The point (0, 0) shows that the hot air balloon is free to ride. B The point (2, 40) shows that the hot air balloon is at a height of 2m after 40 seconds. C None of the above