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
Triple sugar iron agar showing gas production with red slant and yellow butt. The organism cultured is ? 
Select and explain. 
A. E coli, B. Shigella flexneri, C. Pseudomonas, D. None
B: Shigella flexneri
Answer: B: Shigella flexneri 
Explanation: Ans. is 'b' i.e., Shigella flexneri