Which set of points does not represent a one-to-one function?
{(9,5), (4,9), (1,7), (8,8), (1,4)}
{(5,9), (8,3), (0, 0), (1,5), (6, 2)}
{(7,4), (1,7), (4,0), (9,5), (3, 3)}
{(9,7), (2,8), (3, 3), (8, 1), (5, 6)}