Question

Which of the following relations is a function?Select one of the options below as your answer:
A. {(1, 2), (1, 3), (2, 8), (3, 9)}
B. {(1, 2), (2, 3), (3, 4), (4, 5)}
C. {(3, -1), (2, 3), (3, 4), (1, 7)}
D. {(3, 0), (4, -3), (6, 7), (4, 4)}