which relation is a function?
A. (-5,1), (-5,0), (-2,1), (-1,4), (6,2)
B. (-5,1), (-2,0), (-2,2), (3,4), (6,2)
C. (-5,1), (-2,0), (-1,1), (2,4), (6,3)
D. (-5,3), (-2,0), (-1,2), (6,4), (6,3)