Which set of ordered pairs represents a function?
(0, 0), (1, 2), (2, 4), (3, 4)

(0, 1), (1, 2), (2, 3), (2, 4)

{0, 0), (0, 2), (2, 2), (2, 4)

(O0, 1), (1, 3), (1, 5), (2, 6)