Which set of values is not a function?
O (9,5) (10,5) (4,-5) (8,-5)
O (3,4) (4,-3) (7,4) (3, 8)
O (6,-5) (7,-3) (8, -1) (9, 1)
O (2,-2) (5, 9) (-5, -7) (1,4)