PLZ HELP ME I"LL DO ANYTHING
Which set of ordered pairs represents a function?
{(−8,1),(5,−7),(−6,9),(−6,−9)}
{(-2, -3), (2, 1), (2, 6), (4, 9)}
{(-8, 4), (6, 4), (9, 1), (7, -6)}
{(-4, 5), (0, 0), (2, -8), (2, 0)}