A nurse is explaining to a patient with chronic obstructive pulmonary disease (COPD) how gas exchange occurs in the lungs. Which of the following best describes the role and location of the alveoli in this process?

Alveoli are located in the nasal cavity and help warm and humidify the air before it reaches the lungs.

Alveoli are tiny air sacs located at the end of the bronchial tubes where oxygen and carbon dioxide are exchanged

Alveoli are muscular structures in the lungs that contract to help expel air during exhalation.

Alveoli are large cavities in the lungs that filter out dust particles and other pollutants.