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: Physiology
[{'content': 'Negative intrapleural pressure is due to - \nSelect and explain. \nA. Uniform distribution of surfactant over alveoli, B. Negative intraalveolar pressure, C. Absorption by lymphatics, D. Presence of cartilage in the upper airway', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The intrapleural pressure becomes more negative at the end of inspiration and less negative at expiration. It ranges between -3 and -6 mmHg.\xa0\nThe elasticity of lung and rib cage causes it to recoil and thus creating the negative pressure.\xa0\nThe lymphatic drainage of the pleural fluid also creates a negative pressure.', 'role': 'assistant'}]