Exam 1z0-809 topic 1 question 176 discussion

Given:
public class Canvas implements Drawable {
public void draw () { }
}
public abstract class Board extends Canvas { }
public class Paper extends Canvas {
protected void draw (int color) { }
}
public class Frame extends Canvas implements Drawable {
public void resize () { }
abstract void open ();
}
public interface Drawable {
public abstract void draw ();
}
Which statement is true?