Which of the following relations DOES NOT represent y as a function of x?
1. {(2,6),(5,9),(0,8),(6,4)}
II. {(2,9),(2,7),(-8,6),(0,8)}
III. {(9,7),(7,0),(-8,2),(9,4)}
IV. {(7,-2),(-7,0),(0,-6),(3,-4)}
II and III only
I and IV only
I, II, and IV only
O III and IV only