Which of the following relations is also a function? o {(1,6), (1,7), (7,8), (8,9)}
o {(0,1),(0,2), (0,3), (0,4)}
o {(1,1),(3,2), (6,3), (8,4)}
o {(2,3), (3, 2), (2, 4), (4,2)}