Your heart functions in your body as a muscle that helps to pump oxygen around the body. The correct option among all the options given in the question is option "D". The heart is actually a pump that helps to move the blood in different directions. The lungs is the actual place where the exchange of oxygen and carbon dioxide takes place.
Basically the heart is a hollow
organ and its main purpose is to pump the blood to various organs via the arteries
connected with it.
