contestada

Does each relation represent a function? Choose Yes or No.
(1, 3), (2, 5), (2, 7), (4, 9)

(1, 3), (2, 5), (3, 7), (4, 9)

(1, 3), (1, 5), (1, 7), (1, 9)

(1, 3), (2, 3), (3, 3), (4, 3)