What is the effect of attempting to compile this Java program that consists of three definitions in separate files: 
public interface ITwo
{
   public int getX();

   public int getY();
}

public class One
{
   public int getX()
   {  return x;
   }

   private int x;
}

public class Two
   extends One implements ITwo
{
   public int getY()
   {  return y;
   }

   private int y;
}
(a) The program doesn't compile because x is private.
(b) It doesn't compile because Two doesn't implement getX.
(c) It doesn't compile because Two can't both extend a class and implement an interface at the same time.
(d) It compiles.

Select the most appropriate answer.