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: Social & Preventive Medicine
[{'content': 'Index of operational efficiency of Malaria ? \nSelect and explain. \nA. API, B. ABER, C. Infant parasite rate, D. Spleen rate', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., ABER Annual blood examination rate (ABER) is an index of operational efficiency.", 'role': 'assistant'}]