Which set of ordered pairs represents a function?
\{(-6, 5), (-1, -2), (-4, -6), (-9, 5)\}{(−6,5),(−1,−2),(−4,−6),(−9,5)}
\{(-4, -4), (-4, 8), (-7, 1), (9, 7)\}{(−4,−4),(−4,8),(−7,1),(9,7)}
\{(-3, 4), (6, 1), (-8, -8), (-8, -5)\}{(−3,4),(6,1),(−8,−8),(−8,−5)}
\{(7, 9), (0, 4), (-2, 1), (7, 1)\}{(7,9),(0,4),(−2,1),(7,1)}