Which set of ordered pairs does NOT represent a function?
a. ((-3,9), (-2,4), (-1, 1), (0,0), (1.1), (2. 4). (3.9))
b. (1,3), (2, 6), (3,9), (4, 12). (5. 15))
c. (t.1), (4,2). (9. 3). (16,4). (25, 5))
d. 19.-3), (4, -2), (1, -1), (0.0), (1, 1), (4,2). (9. 3)