Which of the following code snippets are the correct way to determine whether a is Odd or Even?

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);