Which set of ordered pairs represents a function?
{(0, 1), (1,3), (1,5), (2, 6)}
{(0, 0), (1, 2), (2, 4), (3, 4);
{(0, 1), (1, 2), (2, 3), (2, 4);
{(0,0), (0, 2), (2, 2), (2, 4);