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 hea to the activated sludge process is ? \nSelect and explain. \nA. Primary sedimentation tank, B. Sludge digester, C. Aeration tank, D. Final settling tank', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Aeration tank o The hea of the activated sludge process is aeration tank.", 'role': 'assistant'}]