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': 'In the gut flora, anaerobic bacteria outnumber the aerobes by a ratio of: \nSelect and explain. \nA. 10:01, B. 100:01:00, C. 1000:01:00, D. 10,000:1', 'role': 'user'}, {'content': "Answer: C \nExplanation: The stomach's acidity keeps the number of microorganisms at a minimum (102-103/mL of contents). In the adult duodenum, there are 103-104 bacteria/mL of effluent; with higher populations in the jejunum, 104-105 bacteria/mL, and ileum, 108 bacteria/mL; and in the cecum and transverse colon, 1011 bacteria/mL. In the sigmoid colon and rectum, the bacteria constitute about 60% of the fecal mass. Anaerobes outnumber facultative organisms by 1000-fold. In diarrhea, the bacterial content may diminish greatly, but in intestinal stasis, the count rises. Ref: Brooks G.F. (2013). Chapter 10. Normal Human Microbiota. In G.F. Brooks (Ed), Jawetz, Melnick, & Adelberg's Medical Microbiology, 26e.", 'role': 'assistant'}]