contestada

Select ALL sets that are functions:
(-2,1), (0.5), (-6, 4), (-2,3)
(-6, 4), (8,3), (2, 2). (10,-5)
(-2,1), (0.5), (-6, 4), (-2, 1)
(5, 16), (6, 20), (7, 25), (9, 10)