I'm not saying desks and stuff aren't furniture, I was more saying that if you have a desk in your room you're going to have something on that desk. Sure, basically everything goes on furniture but you can redecorate your room without moving furniture at all, like by moving decorations/figures/whatever from one piece of furniture to another or putting some away/adding more or changing how things are displayed on said furniture. You can add tablecloths and posters and do all kinds without moving any furniture. Often people use "redecorate" to mean change/move the decorations in a room hence why the quiz says "including furniture" as you don't need to change/move furniture in order to redecorate.