Question

Which relation is a function?








A.
{(1, 2); (2, 3); (3, 4); (2, 5)}







B.
{(1, 2); (2, 3); (3, 4); (1, 5)}







C.
{(1, 2); (2, 5); (3, 2); (4, 5)}







D.
{(1, 2); (1, 3); (3, 2); (4, 2)}