4. Which of the following represents a function?
(8,3), (8,3), (-8, -3), (-8, -3)
0 (-5, 6), (-5, 6), (-5, -6), (-5, -6)
O (3,9), (-7, 1), (6, 12), (-3, -9)
O (5, 1), (5,2), (5, 3), (5, 4)