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
Negative intrapleural pressure is due to - 
Select and explain. 
A. Uniform distribution of surfactant over alveoli, B. Negative intraalveolar pressure, C. Absorption by lymphatics, D. Presence of cartilage in the upper airway
C: Absorption by lymphatics
Answer: C: Absorption by lymphatics 
Explanation: The intrapleural pressure becomes more negative at the end of inspiration and less negative at expiration. It ranges between -3 and -6 mmHg. 
The elasticity of lung and rib cage causes it to recoil and thus creating the negative pressure. 
The lymphatic drainage of the pleural fluid also creates a negative pressure.