31. 執行下列程式片段，其結果為何？solution(6);float solution(int n){if (n == 0)return 1;else if (n == 1)return (2 * solution(n-1));else if (n == 2)return (3 * solution(n-2));elsereturn (n * solution(n-1));}
(A)720
(B)1080
(C)1440
(D)2160