W) {(8, 9), (2, 3), (0, -2), (10, -9)}
x) {(0, 0), (5, 10), (-3, 3)}
y) {(1, 1), (2, 2), (3, 3), (4, 4)}
z) {(-10, 1), (-9, 3), (-4, 5)}
which of the sets represent functions?

a. w, x
b. x, y,z
c. w, z
d. w, x,y, z