Which methods from the String and StringBuffer classes modify the object on which they are called？（）  

Which is the earliest line in the following code after which the object created on the line marked （0） will be a candidate for being garbage collected， assuming no compiler optimizations are done？ （） 
public class Q76a9 {  
static String f（） {  
String a = "hello"；  
String b = "bye"； // （0） 
 String c = b + "!"； // （1）  
String d = b；  b = a； // （2）  
d = a； // （3）  
return c； // （4）  }  
public static void main（String args[]） { 
 String msg = f（）；  
System.out.println（msg）； // （5） 
 }  
}  

Which statements can be inserted at the indicated position in the following code to make the program write 1 on the standard output when run？（） 
public class Q4a39 { 
int a = 1；  
int b = 1；  
int c = 1；  
class Inner {  
int a = 2；  int get（） {  
int c = 3；  
// insert statement here  return c； 
 }  
}  Q4a39（） {  
Inner i = new Inner（）；  
System.out.println（i.get（））；  }  
public static void main（String args[]） { 
 new Q4a39（）； 
 }  
}