This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Myxo Viruses, Subject name: Microbiology
[{'content': 'Swine flu is caused by? \nSelect and explain. \nA. H1N1, B. H5N1, C. H3N1, D. H3N3', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) H1N1REF: See APPENDIX-69 for details of "H1N1 influenza"Repeat (**)', 'role': 'assistant'}]