Which function has an inverse that is also a function?
{(-4, 3), (-2, 7), (-1, 0), (4, -3), (11, -7)}
{(-4, 6), (-2, 2), (-1, 6), (4, 2), (11, 2)}
{(-4,5), (-2, 9), (-1, 8), (4, 8), (11, 4)}
{(-4,4), (-2,-1), (-1,0), (4, 1), (11, 1)}