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': 'The sewage ground water is disposed by \nSelect and explain. \nA. Oxidation pond, B. Activated sludge process, C. Soakage pit, D. Any of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]