Which set of ordered pairs does NOT represent y as a function of x?
A) {(1, 2), (1, 3), (1, 1)}
B) {(1, 1), (2, 2), (-2, 3)}
C) {(1, 2), (2, 3), (3, 3)}
D). {(1, 1), (2, 1), (3, 1)}