"Why?"

Eli just began speaking a ton within the last 2 months. He is now speaking in 2-3 word sentences most of the time and is willing to try just about any word he hears immediately. One habit he has picked up quickly is asking "Why?" when I tell him to do something he doesn't want to do. Just now he knocked down all the blocks I just picked up for him in exchange for him picking up the kitchen toys. Immediately after I was done he went and knocked the blocks all over again. So yes he will be picking them up himself this time. But instead of yelling I just said "Eli go to your room". His response, "Why?".