The epiglottis:

A. Osmosis: Osmosis refers to the movement of water across a membrane, not gases.

B. Active transport pump: Gas exchange does not require energy; it is a passive process, not active transport.

C. Filtration: Filtration is driven by hydrostatic pressure and is more relevant to kidneys and capillary exchange of fluids.

D. Diffusion: Diffusion is the passive movement of gases from an area of higher concentration to an area of lower concentration-how O₂ and CO₂ exchange occurs across the alveolar-capillary membrane.

A. Bronchial tree: The bronchial tree refers to the entire system of airways including the trachea, bronchi, and bronchioles.

B. Bronchioles: Bronchioles are smaller airways that arise from bronchi and do not contain cartilage. They are located further down the respiratory pathway, closer to labels #5 or #6.

C. Alveoli: Alveoli are the tiny air sacs at the very end of the respiratory tract where gas exchange occurs. They are shown at label #7, not #3.

D. Bronchi: Bronchi are the major air passages that branch off from the trachea. Label #3 is pointing to a structure at this level-larger than bronchioles but smaller than the trachea. It is one of the primary or secondary bronchi.