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': 'Gastro-intestinal enteritis necroticans caused by: \nSelect and explain. \nA. CI difficile, B. CI. perfringens, C. Botulinum, D. C jejuni', 'role': 'user'}, {'content': 'Answer: B \nExplanation: “Necrotizing enteritis (enteritis necroticians, or pig bel) is caused by β toxin produced by type C strains of C.perfringens following ingestion of a high protein meal in conjunction with trypsin inhibitors by a susceptible host who has limited intestinal proteolytic activity”. Source of organism is patient own intestinal flora.\nClinical features\n\nAcute abdominal pain, diarrhea, vomiting, shock and peritonitis, 40% of patient die.\nPathological studies shows an acute ulcerative process of the bowel restricted to small intestine.', 'role': 'assistant'}]