单选题

下列程序的运行结果是（） #includeusing namespace ...

Question

下列程序的运行结果是（）

#includeusing namespace stdclass B{public:void show(){cout<<"B"}}class D:public B{public:void show(){cout<<"D"}}void fun1(B ptr){ptr.show()}void fun2(B &ref){ref.show()}void fun3(B b){b->show()}
int main()
{
B b,int main(){B b,p=new DD dfun1(b)fun2(d)fun3(p)return 0}

A. DBB

B. BBD

C. BBB

D. BDD