Which three demonstrate an “is a” relationship？（） 

A、A. public class X {  }     public class Y extends X { }

B、B. public interface Shape { }     public interface Rectangle extends Shape{ }

C、C. public interface Color { }     public class Shape { private Color color； }

D、D. public interface Species { }     public class Animal { private Species species； }

E、E. public class Person { }    public class Employee {      public Employee（Person person） { }

F、F. interface Component { }     class Container implements Component {   private Component[] children； }