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': "Small airways have laminar air flow because: \nSelect and explain. \nA. Reynold's number > 2000, B. Very small diameter, C. Extremely low velocity, D. Low cross sectional area", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Small airway have low reynold number, large cross sectional area, large diameter and air flows at a very low velocity. Ref: Physiology of respiration By Michael P. Hlastala, Albe J. Berger, Page 52; Review of Medical Physiology by William ganong, 22nd edn/page 583', 'role': 'assistant'}]