Question

Look at these sets of ordered pairs.
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