This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'The best indicator for a potential explosiveness of plague outbreak is- \nSelect and explain. \nA. Total flea index, B. Cheopis index, C. Specific percentage of fleas, D. Burrow index', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Question repeated', 'role': 'assistant'}]