Which of the following statments are the correct way to call the method Issue() defined in the code snippet given below?

namespace College
{
    namespace Lib
    {
        class Book
        {
            public void Issue()
            {
                // Implementation code
            }
        }
        class Journal
        {
            public void Issue()
            {
                // Implementation code
            }
        }
    }
}

1. College.Lib.Book b = new College.Lib.Book(); 
   b.Issue();

2. Book b = new Book(); 
   b.Issue();

3. using College.Lib; 
   Book b = new Book(); 
   b.Issue();

4. using College;
   Lib.Book b = new Lib.Book(); 
   b.Issue();

5. using College.Lib.Book; 
   Book b = new Book(); 
   b.Issue();