Exam 1z0-809 topic 1 question 161 discussion

Given the code fragments:
class ThreadRunner implements Runnable {
public void run () { System.out.print ("Runnable") ; }
}
class ThreadCaller implements Callable {
Public String call () throws Exception {return "Callable"; )
}
and
ExecutorService es = Executors.newCachedThreadPool ();
Runnable r1 = new ThreadRunner ();
Callable c1 = new ThreadCaller ();
// line n1
es.shutdown();
Which code fragment can be inserted at line n1 to start r1 and c1 threads?