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': 'Most common site of osteoporosis- \nSelect and explain. \nA. Humerus, B. Vertebrae, C. Scapula, D. Flat bones', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Most common site of osteoporosis is vertebrae.', 'role': 'assistant'}]