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: Orthopaedics
[{'content': 'Which carpal bone fracture causes median nerve involvement? \nSelect and explain. \nA. Scaphoid, B. Lunate, C. Trapezium, D. Trapeziod', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A palmar pole fracture of lunate may cause carpal tunnel syndrome and median nerve compression.', 'role': 'assistant'}]