in a class from which new the thread can be excution? Reading the question carefully (or as I'd intepret it - concerning whether I'm careful you'll receive differing opinions), I think this quoted part would indicate that start() is the correct answer. The question would seem to be asking how to start a thread from some other class. If you just use run(), a new thread isn't created.
On a side note: Sometimes I don't really understand why the author of a question didn't just directly ask what they were getting at. I can understand trying to
test one's understanding by asking questions in a different way, but sometimes they confuse the situation and obscure the actual purpose of the question too much while adding a possible second (or more) interpretation of the question based on its wording. OK, that's enough blah-blah nonsense from me...