Which relations are functions and which are not functions?
Column A		Column B
1.
{(2, 2), (4, 4), (6, 6), 
(8, 8)}
 2.
{(0, 3), (3, 5), (5, 6), 
(8, 4)}
 3.
{(1, 2), (3, 3), (4, 8), 
(6, 3)}
 4.
{(3, 4), (5, 2), (5, 6), 
(7, 3)}
A.
function
B.
not a function