有如下程序：#include using namespace std;class Base {public:void output() { cout<<1; }virtual void Print() { cout<<′B′; }};class Derived : public Base {public:void output() { cout<<2; }void Print() { cout<<′D′; }};int main(){Base *ptr=new Derived;ptr->output();ptr->Print();delete ptr;return 0;}执行这个程序的输出结果是()。

A. 1B
B. 1D
C. 2B
D. 2D