We do not know if this is a younger or an older child, therefore the answer A seems not to be the best option. Answer B sounds a little more like the answer, because the sentence does not state "please" or show any manners. Answer c sounds rude, because a child shouldn't HAVE to do something as small as put a dirty dish in the sink, when you can kindly do it yourself. D doesn't sound quite right, because it kind of is an order. It still doesn't state "please".