Pleasee help
Which set of ordered pairs does not represent a function?

A\{(8, -9), (7, -3), (6, -9), (9, 7)\}{(8,−9),(7,−3),(6,−9),(9,7)}
B\{(-4, 5), (1, 0), (1, -3), (8, 3)\}{(−4,5),(1,0),(1,−3),(8,3)}
C\{(-7, 5), (5, 5), (-3, 9), (0, -3)\}{(−7,5),(5,5),(−3,9),(0,−3)}
D\{(5, -2), (1, -7), (-3, -3), (-4, -2)\}{(5,−2),(1,−7),(−3,−3),(−4,−2)}