The following code contains the classes Hobbit, Ring, and the creation and start of three Hobbit threads in class Main / main(). 

class Ring {
   String owner = "Who knows";
}
    
class Hobbit extends Thread {
   String name;
   Ring ring;
        
   Hobbit (String name, Ring ring) {
       this.name = name;
       this.ring = ring;
   }
        
   @Override
   public void run() {
       ring.owner = name;
       System.out.println(name + " says: the precious is mine, " + ring.owner);
   }
}
// Class Main 
public static void main(String[] args) {
    Ring ring = new Ring();
    Hobbit gollum;
    Hobbit bilbo;
    Hobbit frodo;
 
    gollum = new Hobbit("Gollum",ring);
    bilbo = new Hobbit("Bilbo Baggins",ring);
    frodo = new Hobbit("Frodo Baggins",ring);
    
    gollum.start();
    bilbo.start();
    frodo.start();
 }

Which of the following statements assure mutual exclusion and thus, lead to the expected, thread-safe output?

a) Changing run() in class Hobbit to:

@Override
synchronized public void run() {
   ring.owner = name;
   System.out.println(name + " says: the precious is mine, " + ring.owner);
}

b) Changing run() in class Hobbit to:

@Override
public void run() {
   synchronized(ring) {
      ring.owner = name;
      System.out.println(name + " says: the precious is mine, " + ring.owner);
   }
}

c) Changing the creation of the threads in Class Main (main()) as follows:

synchronized (ring) {
   gollum = new Hobbit("Gollum",ring);
   bilbo = new Hobbit("Bilbo Baggins",ring);
   frodo = new Hobbit("Frodo Baggins",ring);
}

d) Changing the starting of the threads in main() as follows:

synchronized (ring) {
   gollum.start();
   bilbo.start();
   frodo.start();
}