Which set(s) of ordered pairs represents y as a function of x? (Select all that apply.)
a) (9,10), (2,-1), (-3,4), (0,5)
b) (8,2), (2,8), (7,4), (1,0)
c) (7,-3), (4,-9), (-2,-3), (5,-9)
d) (5,2), (5,0), (5,-1), (5,-2)