20. Given the following class definition:

	public class DerivedDemo extends Demo
	{
	int M, N, L ;
	public DerivedDemo( int x, int y )
	{
	M = x ; N = y ;
	}
	public DerivedDemo( int x )
	{
	super( x );
	}
	}

    Which of the following constructor signatures MUST exist
    in the Demo class for DerivedDemo to compile correctly?
    
    Select 2 correct answers:
A. public Demo( int a, int b )
B. public Demo( int c )
C. public Demo( )