Which set of ordered pairs does not represent a function? 1-{(0,6),(5,−4),(3,−4),(8,−6)}

2- {(6,−1),(−6,−1),(−2,−8),(−4,9)}

3-{(−3,−3),(4,1),(−3,3),(2,2)}

4-{(1,−4),(5,−7),(−3,−6),(−2,−4)}