1. import java.util.*； 
2. public class Example { 
3. public static void main（String[] args） { 
4. // insert code here 
5. set.add（new integer（2））； 
6. set.add（new integer（l））； 
7. System.out.println（set）； 
8. } 
9. } 
Which code， inserted at line 4， guarantees that this program will output [1，2]？ （）

A. Cat is-a Animal
B. Cat is-a Jumper
C. Dog is-a Animal
D. Dog is-a Jumper
E. Cat has-a Animal
F. Beagle has-a Tail
G. Beagle has-a Jumper

A. Inheritance represents an is-a relationship.
B. Inheritance represents a has-a relationship.
C. Interfaces must be used when creating a has-a relationship.
D. Instance variables can be used when creating a has-a relationship.

A. Has-a relationships should never be encapsulated.
B. Has-a relationships should be implemented using inheritance.
C. Has-a relationships can be implemented using instance variables.
D. Is-a relationships can be implemented using the extends keyword.
E. Is-a relationships can be implemented using the implements keyword.
F. An array or a collection can be used to implement a one-to-many has-a relationship.
G. The relationship between Movie and Actress is an example of an is-a relationship.