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
Laminar flow is dependent ona) Critical velocityb) Viscosityc) Constant velocityd) Critical closing pressure 
Select and explain. 
A. ab, B. a, C. ad, D. bc
A: ab
Answer: A: ab 
Explanation: The flow of blood (Laminar or turbulent) depends on
-        Fluid density (S)
-        Tube diameter (D)
-        Velocity of fluid (V)
-        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.