This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
[{'content': 'In a section of lung tissue consisting dominantly of alveoli, a tubule about 2mm in diameter is observed that contains smooth muscle and cailage in its wall. The tubule is which one of the following? \nSelect and explain. \nA. Alveolar duct, B. Alveolar sac, C. Bronchiole, D. Bronchus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Any tubule with cailage in its wall and contained in the parenchyma of the lung is a bronchus. Alveolar ducts, alveolar sacs, and bronchioles do not contain cailage. The trachea lies outside of the lung.', 'role': 'assistant'}]