Which of the following sets of ordered pairs does not define a function?

{(1,2),(5,6),(6,7),(10,11),(13,14)}
{(−1,4),(0,4),(1,4),(2,4),(3,4)}
{(1,1),(2,2),(3,3),(4,4),(5,5)}
{(1,3),(5,2),(6,9),(1,12),(10,2)}