Which of the following statements are true?

1. The wait(), notify(), and notifyAll() methods 
   must be executed in synchronized code.
2. The wait method defined in the Thread class, 
   can be used to convert a thread from Running state 
   to Waiting state.
3. The notify() and notifyAll() methods can be used 
   to signal and move waiting threads to ready-to-run state.
4. The Thread class is an abstract class.