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': 'All of the following statements about cholera are true except - \nSelect and explain. \nA. 0 & H antigens measure carrier state, B. Culture medium is TCBS Agar, C. Produces indole and reduces nitrate, D. Synthesize neuraminidase', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., 0 & H antigens measure carrier state", 'role': 'assistant'}]