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

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.

1. A class
2. A property
3. A struct
4. A function
5. An interface

acc.accountNo = 10; 
Console.WriteLine(acc.accountNo);

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;