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': 'A type of tertiary waste water treatment process is – \nSelect and explain. \nA. Reverse osmosis, B. Sedimentation, C. Both, D. Neither', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]