Question

Identify the relation that is also a function.
A.
{(4, 2) (4, -3) (9, 3) (9, -3)}
B.
{(1, 0) (2, 3) (3, -1) (1, 5)}
C.
{(0, -1) (1, -2) (2, -3) (-1, 2)}
D.
{(5, 4) (5, 1) (5, 3) (0, 5)}

D???

Answer 1

pick the one where no x-value (1st element) is repeated.

Sadly, not D.
You cannot have f(5) = 4 and also f(5) = 1.