Question

which best explains how a heat pump can heat a room?
cold air from the house is moved through pipes, where it absorbs thermal energy.
warm air from outside is pushed into the house to replace the cold air.
combustion warms the air when chemical energy is transferred to thermal energy.
fuel is used to move a piston, which pushes warm air into the house.

Explanation:

A heat pump works by transferring heat, not generating it via combustion or using fuel - based piston movement. It moves cold air from the house through pipes (like in a refrigeration - cycle - based system), and this cold air absorbs thermal energy (from outside, for example) and is then used to heat the room. The option about warm air from outside being pushed in is incorrect as heat pumps don't just push external warm air; the option with combustion is for systems like furnaces, and the fuel - piston option is for engine - based heating which is not how heat pumps work.

Answer:

A. Cold air from the house is moved through pipes, where it absorbs thermal energy.