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: Medicine
[{'content': 'WHO Ladder is for the rationale titration of \nSelect and explain. \nA. Oral analgesia, B. Chemotherapy, C. Radiotherapy, D. Antidepressants', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]