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': 'MC commensal gut flora in adult - \nSelect and explain. \nA. Lactobacillus, B. Bacteroides, C. E. coli, D. Klebsiella', 'role': 'user'}, {'content': 'Answer: B \nExplanation: In the human intestines, Anaerobes out number aerobic bacteria a thousand fold\nAmong anaerobes Bacteroides are in predominant number in human gut flora.', 'role': 'assistant'}]