Question

Which of the following relations is a function?

Select one:
a. {(2, 0), (2, 1), (2, 2), (2, 3)}
b. {(0, 2), (1, 2), (2, 2), (3, 2)}
c. {(4, 5), (6, 7), (8, 9), (8, 11)}
d. {(3, 5), (4, 7), (5, 9), (5, 11)}