11.class Snoochy{
12.Boochybooch；
13.public Snoochy（）{booch=newBoochy（this）；}
14.}
15.
16.class Boochy{
17.Snoochy snooch；
18.public Boochy（Snoochys）{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 objectrbo？（）