Which set of ordered pairs represents y as a function of x?
O {(1,5), (2,5), (3,4), (1,4)}
O {(7,8), 6,2), (3,2), (6,7)}
{(0,9), (2,8), (3,5), (1,8)}
o {(7,3), (2,6), (1,4), (2,8)}