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': 'At present following types of influenza viruses are circulating in the world, except- \nSelect and explain. \nA. H1N1, B. H3N2, C. H5N1, D. B virus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: At present three types of influenza viruses are circulating in the world : A (H1N1), A (H3N2) and B virus. WHO global surveillance activities have identified human infection with a new influenza viruse called A (H5N1) in Hong Kong in mid 1997. However, the possibility that the outbreak heralded a global influenza pandemics did not materialize. Ref: PARK&;S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE , 23rd edition , Page :153', 'role': 'assistant'}]