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': 'Most common cause of gas gangrene ? \nSelect and explain. \nA. Cl welchii, B. Cl septicum, C. Cl novyi, D. Cl histolyticum', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., CI welchii Most common cause of gas gangrene is Cl perfringens (Cl welchii) causing 80% of cases of gas gangrene. Other causes are Cl septicum, Cl novyi and Cl histolyticum.", 'role': 'assistant'}]