If Norton is scheduled for the fifth performance, which one of the following could be true?

So I understand that just because N is 5 that doesn't mean that L has to be 3 but you can put them in an order with N being 5 and L being 3 that doesn't violate any rules, ex: O P L M N K J (which is what I concluded) so I guess my question is, O performing first could also be true so how can we figure out which answer is correct if there two could be true?