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