Which of the following statement is correct about the program given below?

#include<iostream.h> 
class Tab
{
      int x; 
    public:
      Tab();
     ~Tab();
      void Show() const;
};
Tab::Tab()
{
    x = 25;
}
void Tab::Show() const
{
    cout<< x;
}
int main()
{
    Tab objB;
    objB.Show();
    return 0; 
}

class Birds {};
class Peacock : protected Birds {};

#include<iostream.h> 
int main()
{
    int x = 80; 
    int &y = x;
    x++;
    cout << x << " " << --y;
    return 0;
}

#include<iostream.h> 
class A
{
    public:
    void CuriousTabFunction(void)
    {
        cout<< "Class A" << endl;
    }
};
class B: public A
{
    public:
    void CuriousTabFunction(void)
    {
        cout<< "Class B" << endl;
    } 
};
class C : public B
{
    public:
    void CuriousTabFunction(void)
    {
        cout<< "Class C" << endl;
    } 
};
int main()
{
    A *ptr;
    B objB;
    ptr = &objB;
    ptr = new C();
    ptr->CuriousTabFunction();
    return 0; 
}