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': 'In total flea index true is - \nSelect and explain. \nA. Average all Xenopsella cheopis per rat, B. Average number of all fleas of all species per rat, C. Average number of all fleas in a burrow, D. Average number of all fleas in all species of rats to per burrow', 'role': 'user'}, {'content': 'Answer: B \nExplanation: <p> Total flea index: it is the average number of flea of all species per rat. Reference:Park&;s textbook of preventive and social medicine,K.Park,23rd edition,page no:294 <\\p>', 'role': 'assistant'}]