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: Dental
[{'content': 'The heart of activated sludge process is? \nSelect and explain. \nA. Aeration tank, B. Primary sedimentation, C. Digestion tank, D. Secondary sedimentation tank', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Sludge is managed aerobically; Aeration which is the heart of the sludge process is done in aeration tank.', 'role': 'assistant'}]