单选题 有如下程序：#include＜iostream＞using namespace std；class Base{public：void fun1(){cout＜＜"Base＼n"；}virtual void fun2(){cout＜＜"Base＼n"；}}；class Derived：public Base{public：void fun1(){cout＜＜"Derived＼n"；}void fun2(){cout＜＜"Derived＼n"；}}；void f(Base& b){b．fun1()；b．fun2()；}int main(){Derived obj；f(obj)；return0；}执行这个程序的输出结果是( )。