Question

Which relation is a function?

{(8, 1), (4, 1), (0, 1), (–15, 1)}
{(0, 1), (0, 2), (1, 2), (1, 3)}
{(–2, –12), (–2, 0), (–2, 4), (–2, 11)}
{(–4, –6), (–3, –2), (1, –2), (1, 0)}

Answer 1

I think it's fourth or third