People who run this sort of question usually allow for a bit of partial credit. It's not pass/fail. If you write something that's wrong, but you can at least

People who run this sort of question usually allow for a bit of partial credit. It's not pass/fail. If you write something that's wrong, but you can at least point out why it's wrong, then that's not a good answer, but it's not always an immediate disqualification.