Which of the following statements is correct?

namespace CuriousTabConsoleApplication
{ 
    struct Sample
    {
        public int i;
    }
    class MyProgram
    { 
        static void Main(string[] args)
        {
            Sample x = new Sample();
            Sample y;
            x.i = 9;
            y = x;
            y.i = 5;
            Console.WriteLine(x.i + " " + y.i); 
        } 
    } 
}

namespace CuriousTabConsoleApplication
{ 
    struct Sample
    {
        public int i;
    }
    class MyProgram
    { 
        static void Main()
        {
            Sample x = new Sample(); 
            x.i = 10; 
            fun(x); 
            Console.Write(x.i + " ");
        }
        static void fun(Sample y)
        {
            y.i = 20; 
            Console.Write(y.i + " ");
        } 
    } 
}

class Trial
{ 
    int i; 
    Decimal d;
}
struct Sample
{
    private int x; 
    private Single y; 
    private Trial z;
}
Sample samp = new Sample();

struct Book
{
    private String name; 
    protected int totalpages; 
    public Single price; 
    public void Showdata()
    {
        Console.WriteLine(name + " " + totalpages + " " + price);
    } 
    Book()
    {
        name = " "; 
        totalpages = 0;
        price = 0.0f; 
    } 
} 
Book b = new Book();

1. We cannot declare the access modifier of totalpages as protected.
2. We cannot declare the access modifier of name as private.
3. We cannot define a zero-argument constructor inside a structure.
4. We cannot declare the access modifier of price as public.
5. We can define a Showdata() method inside a structure.

struct Emp
{
    private String name; 
    private int age; 
    private Single sal;
}

1. Emp e(); e = new Emp();
2. Emp e = new Emp;
3. Emp e; e = new Emp;
4. Emp e = new Emp();
5. Emp e;

namespace CuriousTabConsoleApplication
{ 
    struct Sample
    { 
        public int i;
    }
    class MyProgram
    { 
        static void Main(string[] args)
        {
            Sample x = new Sample(); 
            x.i = 10; 
            fun(ref x); 
            Console.Write(x.i + " ");
        }
        public static void fun(ref Sample y)
        { 
            y.i = 20;
            Console.Write(y.i + " "); 
        } 
    } 
}

class Trial
{ 
    int i;
    Decimal d;
}
struct Sample
{
    private int x;
    private Single y;
    private Trial z;
}
Sample ss = new Sample();