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': 'Commonest age group for diptheria is - \nSelect and explain. \nA. 1-2 Years, B. 1-5 Years, C. 2-7 Years, D. 2-9 Years', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Diphtheria paicularly affects children aged 1 to 5 yrs. In countries where widespread immunization practised, a shift in age incidence has been observed from preschool to school age. Ref:PARK&;S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 23rd edition , Page :160', 'role': 'assistant'}]