This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System Pa 1, Subject name: Physiology
TRUE Concerning airflow in the lung is: 
Select and explain. 
A. Flow is more likely to be turbulent in small airways than in the trachea, B. The lower the viscosity, the less likely is turbulence to occur, C. In pure laminar flow, halving the radius of the airway increases its resistance eight fold, D. Airway resistance increases during scuba diving
D: Airway resistance increases during scuba diving
Answer: D: Airway resistance increases during scuba diving 
Explanation: During scuba diving, the density of the air is increased because of the raised pressure, and therefore, airway resistance rises. The other choices are incorrect: Flow is most likely to be turbulent in large airways; The higher the viscosity, the less likely is turbulence to occur; Halving the radius of the airway increases its resistance 16-fold;