Question

Select all the sets that are functions.

{69, 82, 44, 37}
{(19, 4), (52, 18), (29, 17), (3, 4)}
{(4, 9), (4, 4), (4, 29), (4, 19)}
{(4, 3), (, 29), (, 52), (4, 19)}
{(1, 1), (1, 2), (4, 3), (4, 4), (9, 5), (9, 6)}