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
[{'content': 'Diffusion of gas in the respiratory membrane \nSelect and explain. \nA. Directly proportional to thickness of respiratory membrane, B. Inversely proportional to molecular weight of the gas, C. No lipid - water solubility, D. Inversely proportional to pressure gradient', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The rate of diffusion of gas across the respiratory membrane is\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Directly proportional to \n\nThe pressure gradient across the membrane\nLipid solubility of the gas \nThe surface area of the membrane\n\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Inversely proportional to\n\nThe thickness of the membrane\u200b\nThe molecular weight of the gas', 'role': 'assistant'}]