Which set of ordered pairs does not represent a function?
O {(6, 7), (-4,-5), (-1, 7), (-9, -7)}
O{(-6, 1), (-9, -6), (6, 7), (1, -8)}
O {(5,9), (7,2), (1,6), (-6,9)}
O {(-1, 1), (4, -6), (-3,0), (-3, 8)}