Question

Which set of ordered pairs represent y as a function of x?
A. {(-9, 2), (0, 6), (1, -2), (-3, 6)}
B. {(-1, 0), (4, 3), (-7, -3) (-1, -8)}
C. {(3, 2), (-4, -2), (3, 1), (-4, 1)}
D. {(5, 4), (2, 3), (1, 1), (2, 4)}