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': 'Which of the following lead to an outbreak of Influenza in China in 2013 - \nSelect and explain. \nA. H\n1\nN\n1, B. H\n3\nN\n2, C. H\n2\nN\n2, D. H\n7\nN\n9', 'role': 'user'}, {'content': 'Answer: D \nExplanation: In china, there was an outbreak of influenza caused by Avian influenza H7N9, in 2013.\nIt started in china and spread to Hong Kong.\nMost common age group affected was older male (> 50 years).', 'role': 'assistant'}]