Select the possible values of the result variable after executing the following code:
ExecutorService executorService = Executors.newSingleThreadExecutor();
List<Callable<String>> callableList = new ArrayList<>();
callableList.add(() -> "Java is the best");
callableList.add(() -> "Java is the very best");
callableList.add(() -> "Java is an island");
String result = executorService.invokeAny(callableList);