This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
[{'content': 'Oxidation pond is used in _____ treatment \nSelect and explain. \nA. Sewage, B. Effluent, C. Night soil, D. Sullage', 'role': 'user'}, {'content': "Answer: A \nExplanation: Oxidation ponds: It is a cheap method of sewage treatment Aka waste stabilization pond, redox pond, sewage lagoons, etc. It is an open shallow pool 1 to 1.5 m deep with an inlet and outlet there must be the presence of algae, ceain bacterias, and sunlight. Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 825", 'role': 'assistant'}]