Which of the following statements are correct about subroutines used in C#.NET?

1. If we do not return a value from a subroutine then a value -1 gets returned.
2. Subroutine definitions cannot be nested.
3. Subroutine can be called recursively.
4. To return the control from middle of a subroutine exit subroutine should be used.
5. Subroutine calls can be nested.