Question about threads

[Adolfo Eloy]

Hi everyone.
Considering the exercise that follows:

Question from MasterExam A mock exam.

Assuming that an interrupted exception has NOT been thrown and that "aLiveThread" is a runnable thread, which three guarantee that a thread will leave the running state?

Answers:
wait()
sleep(1000)
aLiveThread.join()

I didn't understand why does the aLiveThread.join() is a correct answer.
Could anyone help me with this?

Thanks

[Deepak Bala]

join() is a blocking call that waits for aLiveThread to complete before the thread that called aLiveThread.join() can continue. Any thread that joins another thread cannot run until the target thread completes

[Adolfo Eloy]

Thanks Deepak. I understand now.