The graph below shows the motion of a car leaving the airport with segments A, B, and C labeled on their journey. Speed vs time graph; coordinates (0, 0), (1, 3), (2, 3), (3, 2), (4, 1), (5, 1), (6, 3), (7,5). Segment A is (1, 3), (2, 3), segment B is (2, 3), (3, 2), (4, 1), and segment C is (5, 1), (6, 3), (7,5). Identify the line segment that would represent a zero acceleration. Explain your answer.