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: Social & Preventive Medicine
[{'content': 'Not a feature of septic tank \nSelect and explain. \nA. Used where public sewerage system is adequate, B. Water tight compartment, C. Used where water supply is adequate, D. Used for personal and small public use', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]