This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Physiology
When gases flow through an orifice which factor is least likely to affect turbulence 
Select and explain. 
A. Density of gas, B. Viscosity of gas, C. Pressure of gas, D. Diameter of orifice
C: Pressure of gas
Answer: C: Pressure of gas 
Explanation: Ans. (c) Pressure of gas(Ref: Ganong, 25th ed/p.629)Whether the air flow is laminar or turbulent is determined by Reynolds numberReynolds number =rDV/eWhere,r-Density of the gasD-Diameter of the airwaysV -Velocity of gase -Viscosity of gasPressure of gas is not in the formula for Reynolds number