This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Poiseuifte's law is 
Select and explain. 
A. F = (PA - PB) pr4/8e4, B. F = (PA x PB) pr4/8e1, C. F = (PA + PB) pr4/8e1, D. F = (PA / PB) pr4/8e1
A: F = (PA - PB) pr4/8e4
Answer: A: F = (PA - PB) pr4/8e4 
Explanation: By integrating the velocities of all the concentric rings of flowing blood and multiplying them by the areas of the rings, one can derive the following formula, known as Poiseuille's law: in which F is the rate of blood flow, DP(PA-PB) is the pressure difference between the ends of the vessel, r is the radius of the vessel, l is length of the vessel, and e is viscosity of the blood. F = (PA - PB) pr4/8e4 Ref: Guyton and Hall Textbook of Medical Physiology (12th Edn) page No:309