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