B because maybe he takes a break or go on his phone and he gets glued to his phone instead of doing his homework
Well mathematics argue that B is the correct answer, but at this moment Idiocracy states all the other choices
When they are three they are only in the “preoperational” stage. In this stage they start to develop language, memory, and imagination. But when they are nine, they are in the “concrete operation” stage. In this stage they are more logical and methodical manipulation of symbols. More aware basically.