Which relation is not a function? A. (2, 9), (−1, −5), (1, 5), (5, 0), (12, 3) B. (−3, 1), (6, 2), (8, 3), (6, 4), (3, 5) C. (5, 1), (4, 2), (3, 3), (2, 4), (1, 5) D. (7, 2), (5, 3), (3, 4), (1, 5), (−1, 6)