This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2018, Subject name: Social & Preventive Medicine
[{'content': 'Most impoant factor in sewage treatment: \nSelect and explain. \nA. Bacterial count, B. Solids, C. Nitrite and phosphorus, D. Water content', 'role': 'user'}, {'content': 'Answer: B \nExplanation: sewage treatment in india, is divided into categories : 1. primary - for solids ( most impoant ) 2. secondary - for biological matters 3. teiary - for quality improvement of the sludge', 'role': 'assistant'}]