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
Stability of alveoli is maintained by? 
Select and explain. 
A. Lung compliance, B. Negative intrapleural pressure, C. Increase in alveolar surface area by the surfactant, D. Residual air in alveoli
C: Increase in alveolar surface area by the surfactant
Answer: C: Increase in alveolar surface area by the surfactant 
Explanation: C i.e. Increase in alveolar surface area by the surfactant