Which relations are functions and which are not functions?

Column A Column B

1.

{(3, 7), (3, 6), (5, 4),

(4, 7)}

2.

{(1, 5), (3, 5), (4, 6),

(6, 4)}

3.

{(2, 3), (4, 2), (4, 6),

(5, 8)}

4.

{(0, 4), (3, 2), (4, 2),

(6, 5)}


A.

function

B.

not a function