Which of the relations given by the following sets of ordered pairs is a function?{(1, 1), (1, 3), (1, 5), (1, 7), (1, 9)}
{(-2, 1), (7, 5), (-4,0),(3,1),(0,-6)}
{(1,2),(2,3),(3,4), (3,3),(2,2),(1,1)}
{(2, -8), (1,-4),(1,4), (2,8), (-5,3)}