(pls help asap not much time) Which set of ordered pairs represents y as a function of x?

A) {(2, 5), (3, 1), (2, 1), (4, 7)}


B) {(4, 7), (4, 6), (4, 4), (4, 1)


C) {(3, 2), (4, 3), (5, 2), (2, 6)


D) {(1, 3), (3, 5), (2, 5), (1, 6)