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': 'Kala-azar is not responding to primary treatment. The treatment should now consist of- \nSelect and explain. \nA. Double dose of antimony, B. Amphotericin - B, C. Ketoconazole, D. Splenectorny', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]