Consider the function f(n) defined as: f(0) = f(1) = 1,  and
          f(n) = n(n-1) x f(n-2) for n > 1.

          What should be g(n) to make f(n) = O(g(n)).

          1. g(n) = g(n-1) + n for n > 0 OR g(n) = g(n-1) x n .
          2. g(0) = 0     OR    g(0) = 100.

          SELECT one answer from both 1 and 2.