For a given complexity function f(n), Ω(f(n)) is the set of complexity functions g(n) for which there exists some positive real constant C and some nonnegative integer N such that, for all n >= N, g(n) >= C x f(n).

Which of the following correctly defines Ω (Omega)?

a) The set of complexity functions g(n) for which there exists some positive real constant C and some nonnegative integer N such that, for all n >= N, g(n) <= C x f(n).
b) The set of complexity functions g(n) for which there exists some positive real constant C and some nonnegative integer N such that, for all n >= N, g(n) = C x f(n).
c) The set of complexity functions g(n) for which there exists some positive real constant C and some nonnegative integer N such that, for all n >= N, g(n) > C x f(n).
d) The set of complexity functions g(n) for which there exists some positive real constant C and some nonnegative integer N such that, for all n >= N, g(n) >= C x f(n).