Which set of ordered pairs does not represent a function?

O {(-7, -8), (-7,5), (-6,0),(-1,8)}

O {(-2,4), (6,-5), (-6, -9), (1, -5)}

{(8, -2), (3,9), (-1, -5), (-3,9)}

{(9,7), (2,7), (-8, -3), (-1,1)}