Oh, I see now. I would have answered along the lines of “that he’s willing to go to BS so we can rent out his room,” but that’s just me. I would not have answered in any way that could come across as a (humble)brag.
Answers like “she likes baking” or “she’s the best puzzle maker in the family” do not genuinely answer the question IMO. Are those things that YOU like about your child or are you just trying to get in a few more ECs or amazing traits that she couldn’t wedge into the application otherwise?