Which of the following sets of ordered pairs represents a function ?

A. (-1, 15), (0,10), (0,5), (2,5), (5,-5)

B. (-7, -1), (-7,0), (-7,1), (-7,2), (-7,3)

C. (-5,10), (-3,6), (0,0) (5,10)

D. (-8,3), (-4,3), (0,3), (0,5), (4,5)