This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'Which influenza strain was isolated in 1989 spreading to many other countries? \nSelect and explain. \nA. H2N2, B. H1N1, C. H3N2, D. H5N1', 'role': 'user'}, {'content': 'Answer: B \nExplanation: In 1989, epidemic - the reappearance of swine HINI virus Influenza can occur sporadically, as epidemics or pandemics In 2009, H1N1 Epidemic occurred in Mexico-recent Ref: Baveja 5th ed Pg: 468', 'role': 'assistant'}]