Which of the following graphs is not a function? a. On a coordinate plane, a parabola opens up and goes through (negative 2, 1), has a vertex at (0, 0), and goes through (2, 1). c. On a coordinate, a cubic root function approaches y = negative 3 and y = 3. b. On a coordinate, plane a cubic root function approaches x = negative 3 and x = 3. d. On a coordinate plane, a parabola opens to the right and goes through (1, 1), (0, 0) and (1, negative 1).