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: Medicine
[{'content': 'Difference between upper and lower limb blood pressure is usually - \nSelect and explain. \nA. 5mm, B. 10 mm, C. 30 mm, D. 35mm', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]