Which of the following relations is a function? will give 5stars!

A. (-2, -2), (-9, -5), (3, 8), (3, 2)
B. (-9, 2), (-2, 3), (3, 7), (6, 2)
C. (-9, 0), (-2, 5), (-9, -3), (3, 9)
D. (6, -10), (-9, 7), (6, 6), (-9, 12)