Determine which relation is a function. {(0, 0), (1,−1), (2,−4), (3,−9), (4,−16)} {(2,−6), (2,−2), (2, 0), (2, 3), (2, 7)} {(2, 2), (1, 1), (0, 0), (1, −1), (2,−2)} {(3, 2), (4, 3), (5, −4), (5, 4), (6, 5)}