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': 'Annual blood smear examination rate is an indicator of - \nSelect and explain. \nA. Disease rate (Prevalence), B. Operation effciency, C. % of transmission of malaria, D. Infectivity rate', 'role': 'user'}, {'content': "Answer: B \nExplanation: Prevalence of malaria can be inspected by annual blood smear examination. REF. PARK'S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 21ST EDITION. PAGE NO - 238", 'role': 'assistant'}]