Which function has an inverse that is also a function?

A. {(−1, 2), (0, 4), (1, 3), (5, 14), (7, 4)}
B. {(−1, 3), (0, 4), (1, 5), (5, 4), (7, 2)}
C. {(−1, 4), (0, 4), (1, 2), (5, 3), (7, 1)}
D. {(−1, 4), (0, 4), (1, 2), (5, 3), (7, 1)}