It is all of the above, but ONLY if you do the stretches correctly, and carefully, otherwise, it may be quite dangerous.
Hope this helped!
Answer from: Quest
That's a project for you to do. btw your teacher probably uses a plagiarism detector and if you do copy anything on this site she/ he will find out and instead of getting a good or bad grade you'll get a 0 no exceptions, and they'll probably call ur parents. so do some research ask friends and fam to you.