Answer:
True.
Explanation:
Alveoli are the microscopic structure present deep inside the lungs. Alveoli acts as a basic unit of ventilation. Alveoli are present in the lungs of mammals only.
Alveoli are hollow sac like structures when viewed under the microscope. Alveoli are the main site of the gas exchanges in the mammals. The alveoli are covered by the epithelial layers.
Thus, the correct answer is option (a).
