Carl notices that his window air conditioner takes thermal energy from the room and transfers it to the air outside. He thinks he has found an exception to the rules of physics. Which is the most likely reason he is incorrect?

A. Heat does not flow outside naturally. It requires an input of work by the air conditioner.
B. Heat always flows naturally from inside to outside.
C. The room air is actually warmer than the outside air.
D. The air conditioner is actually taking cold from the outside and transferring it into the room.