单选题 有如下程序：
#include＜iostream＞
using namespace std;
class Base{
public:
virtual void Show(){cout＜＜"B";}
};
class Derived:public Base{
public:
void Show(){cout＜＜"D";}
};
int main(){
Base *p1=new Derived;
Derived *p2=new Derived;
p1-＞Show();
p2-＞Show();
delete p1;
delete p2;
return 0;
}
运行这个程序的输出结果是______。