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': 'Osteoporosis is characterized most commonly by -a) Fracture vertebrab) Backache c) Bowing of legsd) Abdominal pain \nSelect and explain. \nA. ab, B. a, C. ad, D. bc', 'role': 'user'}, {'content': "Answer: A \nExplanation: Clinical features of osteoporosis \n\nOsteoporosis is an asymptomatic disorder unless complications (predominantly fractures) occur.\nMost common symptom of osteoporosis is back pain secondary to vertebral compression fracture.\nDorso-lumbar spine is the most frequent site.\nOther common sites of fracture are lower end radius (Colle's fracture) and fracture neck femur.", 'role': 'assistant'}]