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: Unknown
[{'content': 'Poiseuille’s hagen lawis \nSelect and explain. \nA. F = (PA–PB) × 3.14 × r4/8nl, B. F = (PA+PB) × 3.14 × r4/8nl, C. F = (PA/PB) × 3.14 × r4/8nl, D. F = (PA × PB) × 3.14 × r4/8nl', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Poiseuille-Hagen Formula\nThe relation between the flow in a long narrow tube, the viscosity of the fluid, and the radius of the tube is expressed mathematically in the Poiseuille-Hagen formula:', 'role': 'assistant'}]