Which set of ordered pairs represents y as a function of x?

(0, 0.5), (2, 1.5), (−5.5, 5), (−5.5, −6)

(0, 0.5), (2, 1.5), (2, 5), (2, −6)

(0, 0.5), (0, 1.5), (0 , 5), (−5, −6)

(0, 0.5), (2, 1.5), (−5.5, 5), (−5, −6)