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': 'In endemic area, most sensitive indicator of recent transmission of malaria is \nSelect and explain. \nA. Infant parasite site, B. Spleen rate, C. ABER, D. API', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]