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