单选题 下列程序的运行结果为().#include <iostream>using namespace std;class A{public: A(int i,int j){ x = i; y = j; } int sum(){ return x + y; }private: int x,y;};class B:public A{public: B(int i,int j,int k,int l); int sum(){ return w + h; }private: int w,h;};B::B(int i,int j,int k,int l):A(i,j){ w = k; h = l;}void f(A&s){ cout<<s.sum()<<endl; }int main(){ B ob(1,3,5,7); f(ob); return 0;}