This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Clostridium, Subject name: Microbiology
[{'content': 'Most common organism responsible for gas gangrene is - \nSelect and explain. \nA. Clostridium perfringens, B. Clostridium difficile, C. Clostridium tetani, D. Clostridium septicum', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Clostridium perfringens o Most common cause of gas gangrene is Cl perfringens (Cl welchii). Other clostridia causing gas gangrene are Cl septicum, Cl novyi and Cl histolyticum.", 'role': 'assistant'}]