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？（） 

11. public void genNumbers（） { 
12. ArrayList numbers = new ArrayList（）； 
13. for （int i=0； i<10； i++） { 
14. int value = i * （（int） Math.random（））； 
15. Integer intObj = new Integer（value）； 
16. numbers.add（intObj）； 
17. } 
18. System.out.println（numbers）； 
19. } 
Which line of code marks the earliest point that an object referenced by intObj becomes a candidate for garbage collection？（）