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
Which of the following increases turbulence in blood flow 
Select and explain. 
A. Reynolds number less than 2000, B. Decrease in velocity of blood, C. Decrease in density of blood, D. Increase in diameter of blood vessel
D: Increase in diameter of blood vessel
Answer: D: Increase in diameter of blood vessel 
Explanation: The flow of blood (Laminar or turbulent) depends on
-        Fluid density (S)
-        Tube diameter (D)
-        The velocity of the fluid (V)
-        The viscosity of fluid (n)
This can be expressed by Reynold’s number (R) = SDV/n
Normal flow is laminar. But if the velocity crosses a critical limit (Critical velocity) flow becomes turbulent. If R>2000, flow is turbulent.