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: Medicine
[{'content': 'The endotoxin of the following gram-negative bacteria does not play any part in the pathogenesis of the natural disease - \nSelect and explain. \nA. Escherichia coli, B. Klebseilla spp., C. Vibrio cholerae, D. Pseudomonas aeruginosa', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]