Which set of ordered pairs represents a function?
o{(1,3) (2,5) (4,9) (4, 13)}
o{(1,3) (1,5) (4, 9) (6,3)}
o {(1, 3) (2,5) (2, 9) (6, 13)}
O {(1,3) (2,5) (4, 9) (6,5)}