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);
return 0;

执行这个程序的输出结果是( )。

A．Base
Base
B．Base
Derived
C．Derived
Base
D．Derived
Derived