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': 'The most predominant type of polio virus during epidemics is - \nSelect and explain. \nA. Type I, B. Type II, C. Type III, D. Combined infection of II & III', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Polio virus has three serotypes 1,2 and 3. Most outbreaks of paralytic polio are due to type-1 virus. Ref: PARK&;S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 23rd edition , Page :205', 'role': 'assistant'}]