Answer: C. respiratory
Step-by-step explanation:
The lungs are the vital organs which are the part of the respiratory system. A respiratory system consists of specialized organs both in plants as well as in animals which helps in the process of exchange of gases. The two lungs consists of network of blood vessels and tubes where gaseous (carbon dioxide and oxygen) exchange takes place. The tubes and blood vessels includes the brochioles, the alveoli and the capillaries. The oxygenated blood from the lungs is transported to heart for circulating it to all the parts of the body.