PLZZ HELP I AM IN NEED WILL MARK BRAINLIEST!
Which relation is a function?

A: {(7, 12), (1, -5), (3, -10), (2, -5)}
B: {(1, 2), (1, 5), (1, -1), (1, 4)}
C: {(-3, 4), (-2, 5), (0, 9), (0, 12)}
D: {(8, -1), (2, -1), (3, 8), (2, 5)}