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
Osteoporosis is caused by all, except - 
Select and explain. 
A. Corticosteroid, B. Oestradiol, C. Methotrexate, D. Chronic heparin therapy
B: Oestradiol
Answer: B: Oestradiol 
Explanation: Oestradiol is used to prevent osteoporosis.
Other causes of osteoporosis have been discussed before.