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: Surgery
[{'content': 'The commonest organism seen in peritonitis is - \nSelect and explain. \nA. Escherichia coli, B. Clostridium welchii, C. Staphylococci, D. Klebsiella', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Escherichia coli", 'role': 'assistant'}]