Oracle Exam 1Z0-809 Topic 2 Question 8 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?