Answer:
B. increase
Explanation:
The two lungs are the primary organs of the respiratory system. They sit to the left and right of the heart, within a space called the thoracic cavity. The cavity is protected by the rib cage. A sheet of muscle called the diaphragm serves other parts of the respiratory system, such as the trachea, or windpipe, and bronchi, conduct air to the lungs. While the pleural membranes, and the pleural fluid, allow the lungs to move smoothly within the cavity.
