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': 'Triple sugar iron agar showing gas production with red slant and yellow butt. The organism cultured is ? \nSelect and explain. \nA. E coli, B. Shigella flexneri, C. Pseudomonas, D. None', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Shigella flexneri", 'role': 'assistant'}]