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;

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. The signature of an indexer consists of the number and types of its formal parameters.
2. Indexers are similar to properties except that their accessors take parameters.
3. Accessors of interface indexers use modifiers.
4. The type of an indexer and the type of its parameters must be at least as accessible as the indexer itself.
5. An interface accessor contains a body.

class Student
{
    int[] scores = new int[5] {3, 2, 4,1, 5}; 
    public int this[ int index ]
    { 
        set
        { 
            if (index < 5)
                scores[index] = value; 
            else
                Console.WriteLine("Invalid Index");
        } 
    } 
}

class Student
{
    int[] scores = new int[5] {3, 2, 4, 1, 5};
    public int this[ int index ]
    { 
        get
        { 
            if (index < 5)
                return scores[ index ]; 
            else
            { 
                Console.WriteLine("Invalid Index"); return 0; 
            } 
        } 
        set
        { 
            if (index < 5)
                scores[ index ] = value;
            else 
                Console.WriteLine("Invalid Index"); 
        } 
    } 
}

class Student
{
    int[] scores = new int[5] {3, 2, 4, 1, 5}; 
    public int this[ int index ]
    { 
        get
        { 
            if (index < 5)
                return scores[ index ]; 
                else
                { 
                    Console.WriteLine("Invalid Index"); 
                    return 0; 
                } 
        } 
    } 
}

class Student
{
    int[] scores = new int[5] {3, 2, 4, 1, 5}; 
    public int this[ int index ]
    { 
        get
        {
            if (index < 5)
                scores[ index ] = value; 
            else
            { 
                Console.WriteLine("Invalid Index");
            } 
        }
        set
        { 
            if (index < 5)
                return scores[ index ];
            else
            { 
                Console.WriteLine("Invalid Index");
                return 0;
            }
        }
    }
}