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': 'All are motile, EXCEPT: \nSelect and explain. \nA. Cl.histolyticum, B. Cl.tetanosporum, C. Cl.perfringens, D. Cl.septicum', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C perfringens is a large, Gram-positive, nonmotile rod with square ends. Hemolysis and gas production are characteristic. In broth containing fermentable carbohydrate, growth of C perfringens is accompanied by the production of large amounts of hydrogen and carbon dioxide gas, which can also be produced in necrotic tissues; hence the term gas gangrene. Ref: Ray C.G., Ryan K.J. (2010). Chapter 29. Clostridium, Peptostreptococcus, Bacteroides, and Other Anaerobes. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.', 'role': 'assistant'}]