Which set of ordered pairs does NOT represent y as a function of x?

Question 5 options:

{(1, 1), (2, 2), (2, 3)}

{(1, 2), (2, 3), (3, 3)}

{(1, 1), (2, 1), (3, 1)}

{(1, 2), (1, 3), (1, 1)}

Which set of ordered pairs does NOT represent y as a function of x?

Question 5 options:

{(1, 1), (2, 2), (2, 3)}

{(1, 2), (2, 3), (3, 3)}

{(1, 1), (2, 1), (3, 1)}

{(1, 2), (1, 3), (1, 1)}