Huh, indeed, factfulnessquiz.com seems to be selecting wrong answer as correct even though they list correct answer correctly on http://factfulnessquiz.com/answers

Pretty serious given that there are only 13 questions and that's what the whole website is about. They didn't even leave any contact. I'll send an email to gapminder.

Nice catch, and a really bad job from whoever made the quiz website. Triple checking those answers should be a priority.