If the category is planets, would dwarf planets be considered a planet?
The Event Supervisors (ES) who constructs the grid will be the final arbiter of the correct answer for the grid. ES are encouraged to select categories that are not vague to avoid confusion as this could have a very narrow interpretation to some people while having a very broad interpretation to others. In this case, by choosing a category like “Names of Planets” or “Terms related to planets” the participants would have a much better understanding of acceptable answer choices. ES should select letters that have acceptable answers. ES should also try to avoid choosing letters that have misleading answer choices for the participants.