which of the following are functions

A. [(-2,3)], [(-1,5)], [(0,7)], [(1,9)]
B. [(-3,3)], [(3,3)], [(0,0)], [(1,1)], [(-1,1)]
C. [(-2,5)], [(-1,4)], [(0,3)], [(-1,2)], [(-2,1)]