Which set of ordered pairs represents a function?
o {(5,-2), (-5,2), (-5, -4),(4, -5)}
{(9,6),(-1,7), (9,–7), (4,7)}
o {(-1,0),(-8, 9), (7,0), (1,3)}
{(8,6), (8, –4), (-7, -2),(-1, —8)}