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: Microbiology
[{'content': '7th Pandemic of cholera was caused by - \nSelect and explain. \nA. El Tor, B. 0139 V. cholerae, C. Classical V. cholerae, D. V mimicus', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is `a' i.e., El Tor", 'role': 'assistant'}]