Which of the following statements is correct about classes and objects in C#.NET?

struct Book
{
    private String name; 
    private int noofpages; 
    private Single price;
}
Book b = new Book();

Sample m = new Sample(); 
m.Length = 10;

Sample m = new Sample(); 
m.Length = m.Length + 20;

Sample m = new Sample(); 
int l;
l = m.Length;

Sample.Length = 20;

Console.WriteLine(Sample.Length);

1. Properties
2. Methods
3. Enumerations
4. Events
5. Structures

1. int a;
   String res; 
   if (a % 2 == 0)
       res = "Even"; 
   else 
       res = "Odd";

2. int a; 
   String res; 
   if (a Mod 2 == 0) 
       res = "Even"; 
   else
       res = "Odd";

3. int a;
   Console.WriteLine(a Mod 2 == 0? "Even": "Odd");

4. int a; 
   String res;
   a % 2 == 0? res = "Even" : res = "Odd";
   Console.WriteLine(res);