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