This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Microbiology
[{'content': 'Most sensitive index of recent transmission of malaria in community: \nSelect and explain. \nA. Spleen rate, B. Infant parasite rate, C. Annual parasite rate, D. Slide positivity rate', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b'Annual parasite index measures incidence, spleen rate measures endemicity, ABER-Annual blood examination rate (index of operational efficiency) and SPR (slide positivity rate) - forecasting malaria and defining any area to be high risk or low risk.", 'role': 'assistant'}]