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: Pathology
[{'content': 'Osteoporosis is caused by all, except - \nSelect and explain. \nA. Corticosteroid, B. Oestradiol, C. Methotrexate, D. Chronic heparin therapy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Oestradiol is used to prevent osteoporosis.\nOther causes of osteoporosis have been discussed before.', 'role': 'assistant'}]