Which of the following relationships represents a function?
A.
(-7,5), (2,3), (-9,2), (-1,3)
B.
(-7,4), (2,6), (-7,3), (-1,2)
C.
(-7,0), (2,3), (-9,1), (2,5)
D.
(-4,4), (1,6), (-4,3), (-2,2)