Which set of ordered pairs is not a function?
O
{(0,0), (1,1), (2,2), (3,3)}
O {(1,2), (3,4), (4,5), (5,6)}
O
{(4,1), (5,1), (6,1), (7,1)}
{(3,1), (2,1), (1,2), (3,2)} ​