That is such a lazy study it's pitiful and it does in no way test your ability to discern the veracity of news, so even the full marks I got are useless.
First of all, if you generate fake headlines either test someone's general knowledge or critical thinking, don't conflate the two. Secondly, it's the latter that actually matters the most, so if you build your knowledge based on headlines, you're already close to the fake news group.