Which set of ordered pairs represents a function?

Question

2, –2), (1, 5), (–2, 2), (1, –3), (8, –1)}

{(3, –1), (7, 1), (–6, –1), (9, 1), (2, –1)}

{(6, 8), (5, 2), (–2, –5), (1, –3), (–2, 9)}

{(–3, 1), (6, 3), (–3, 2), (–3, –3), (1, –1)}

Answer 1

The second set represents a function.

The first, third and fourth sets do not represent functions.