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
Poiseuille's law is 
Select and explain. 
A. F = (PA – PB) πr4/8nL, B. F = (PA x PB) πr4/8nL, C. F = (PA + PB) πr4/8nL, D. F = (PA / PB) πr4/8nL
A: F = (PA – PB) πr4/8nL
Answer: A: F = (PA – PB) πr4/8nL 
Explanation: None