On a coordinate plane, a parabola opens up. Solid circles appear on the parabola at (negative 6, 6), (negative 4.5, 2.25), (negative 3, 0), (negative 1.5, negative 0.75), (0, 0), (1,5, 2.25), and (3, 6). Which is the rate of change for the interval between –6 and –3 on the x-axis?