Which relation is a function?
A. (8,-4), (8,4), (6,-3), (6,3), (0, 0)
B. (4, 7), (8,5), (6,4), (5, 3), (4, 2)
C. (0, 0), (1, 1), (2, 2), (3, 3), (4,7)
D. (0, 0). (1, 0), (1, 1), (2, 1), (1, 2)​