Question

which causes the thermal energy in a building to decrease?
the air conditioner and the heat engine
the furnace and the heat pump
the heat pump and the air conditioner
the heat engine and the furnace

Explanation:

• An air - conditioner works by removing heat from the inside of a building and expelling it outside. A heat pump can also be used in cooling mode (similar to an air - conditioner) to remove heat from a building.
• A furnace is used to add thermal energy (heat) to a building. A heat engine, in its typical operation (e.g., in a car), is not directly used to decrease the thermal energy of a building.

Answer:

the heat pump and the air conditioner