Which relations are functions? choose all answers that are correct.
a. {(1, 4), (2, 5), (4, 6), (6, 4)}
b. x 0 2 3 2 y 4 3 8 1
c. a set of points are plotted on a coordinate grid. the points include point 1, point negative 1, point negative 2, point 3, point 2, point negative 3, and point negative 4, 3.
d. a parabola, opening right, is graphed on a coordinate grid. the parabola goes through point 0, 2, point 4, 0, and point 4, 4.