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': 'Most sensitive indicator of recent transmission of malaria of \nSelect and explain. \nA. Infant parasite rate, B. ABER, C. Spleen rate, D. Annual parasite index', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]