Which set of ordered pairs represents a function? {(-9,7), (1,7), (-1, -8), (8,3)}
{(-2, -3), (-2,4), (5,-5),(-1,4)}
{(-3,3), (-7, -2), (-7, -9), (-5,6)}
{(9,6), (8,2), (-8,5), (-8,8)}