A class games.cards.Poker is correctly defined in the jar file Poker.jar. 
A user wants to execute the main method of Poker on a UNIX system using the command： 
java games.cards.Poker 
What allows the user to do this？（） 

1. public class GC { 
2. private Object o； 
3. private void doSomethingElse（Object obj） { o = obj； } 
4. public void doSomething（） { 
5. Object o = new Object（）； 
6. doSomethingElse（o）； 
7. o = new Object（）； 
8. doSomethingElse（null）； 
9.o=null； 
10. } 
11. } 
When the doSomething method is called， after which line does the Object created in line 5 become available for garbage collection？（） 

11. class Snoochy { 
12. Boochybooch； 
13. public Snoochy（） { booch = new Boochy（this）； } 
14. } 
15. 
16. class Boochy { 
17. Snoochy snooch； 
18. public Boochy（Snoochy s） { snooch = s； } 
19. } 
And the statements： 
21. public static void main（String[] args） { 
22. Snoochy snoog = new Snoochy（）； 
23. snoog = null； 
24. // more code here 
25. } 
Which statement is true about the objects referenced by snoog， snooch， and booch immediately after line 23 executes？（） 

11. rbo = new ReallyBigObject（）； 
12. // more code here 
13. rbo = null； 
14. /* insert code here */ 
Which statement should be placed at line 14 to suggest that the virtual machine expend effort toward recycling the memory used by the object rbo？（）