Use the interactive graph to plot each set of points. Which sets represent proportional relationships? Check all that apply.
(3, 1), (6, 2), (9, 3)
(2, 4), (4, 6), (7, 9)
(1.5, 3), (3, 6), (4, 8)
(3, 1), (4, 3), (8, 6)