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: Pharmacology
[{'content': "Methotrexate is used in high doses in - \nSelect and explain. \nA. Osteosarcoma, B. Retinoblastoma, C. Rhabdomyosarcoma, D. Ewig's sarcoma", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Osteosarcoma o High dose methotrexate with leucoverin is indicated for chemotherapy in osteosarcoma.", 'role': 'assistant'}]