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: Pharmacology
[{'content': 'A patient of renal failure has been diagnosed with cholera, so which of the tetracyclines is most suitable for the patient: \nSelect and explain. \nA. Minocycline., B. Doxycycline., C. Oxytetracycline., D. All of the above.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: All tetracyclines are excreted primarily in the urine except doxycycline. Doxycycline is\xa0excreted in the faeces and thus\xa0can be used in the presence of\xa0renal failure.', 'role': 'assistant'}]