Question

Which of the following relations is NOT a function?


A. {(-4, 7), (-9, 0), (0, 6), (2, 9)}
B. {(-4, 7), (-5, 0), (1, 6), (3, 9)}
C. {(-4, 7), (-9, 0), (0, 6), (-4, 0)}
D. {(7, -4), (-9, 0), (0, 6), (2, 9)}