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
[{'content': "Laplace's law, all except \nSelect and explain. \nA. P = T/r, B. P = 2T/r, C. T = Pr/W, D. T = WP/R", 'role': 'user'}, {'content': "Answer: D \nExplanation: Law of Laplace, an impoant physical principle with several other applications in physiology. This law states that tension in the wall of a cylinder (T) is equal to the product of the transmural pressure (P) and the radius (r) divided by the wall thickness (w):T = Pr/w Ref: Ganong's Review of Medical Physiology 25th Edition. Page: 574", 'role': 'assistant'}]