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': 'Which is not a capsulated organism \nSelect and explain. \nA. Pneumococcus, B. Bacillus anthracis, C. H influenza, D. Clostridium tetani', 'role': 'user'}, {'content': 'Answer: D \nExplanation: All clostridia\xa0are non-capsulated except clostridium perfringens.', 'role': 'assistant'}]