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; 
}

#include<iostream.h> 
class CuriousTab
{
    int x, y; 
    public:
    void SetValue(int &xx, int &yy)
    {
        x =  xx++;
        y =  yy; 
        cout<< xx << " " << yy;
    }
};
int main()
{
    int x = 10;
    int &y = x;
    CuriousTab objCuriousTab;
    objCuriousTab.SetValue(x , y);
    return 0; 
}

#include<iostream.h> 
enum xyz
{
    a, b, c
};
int main() 
{
    int x = a, y = b, z = c;
    int &p = x, &q = y, &r = z;
    p = ++x;
    q = ++y;
    r = ++c;
    cout<< p << q << r;
    return 0;
}

#include<iostream.h> 
int main()
{
    int m = 2, n = 6;
    int &x = m;
    int &y = n;
    m = x++; 
    x = m++;
    n = y++;
    y = n++;
    cout<< m << " " << n; 
    return 0; 
}

#include<iostream.h> 
int main()
{
    int arr[] = {1, 2 ,3, 4, 5}; 
    int &zarr = arr;
    for(int i = 0; i <= 4; i++)
    {
        arr[i] += arr[i];
    }
    for(i = 0; i <= 4; i++)
        cout<< zarr[i]; 
    return 0; 
}

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