If Sample class has a Length property with get and set accessors then which of the following statements will work correctly?

1. Sample.Length = 20;

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

3. Console.WriteLine(Sample.Length);

4. Sample m = new Sample(); 
   int len;
   len = m.Length;

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