This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Diffusion is inversely related to: \nSelect and explain. \nA. Molecular size, B. Area, C. Concentration gradient, D. Solubility', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Diffusion is directly propoional to area, solubility, concentration gradient It is inversely related to thickness and molecular size', 'role': 'assistant'}]