When solving a system of inequalities or just an inequality (like 2-4y > 14), in what condition the sign flip to the other way?

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