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 function of grit chamber in modern sewage plants is \nSelect and explain. \nA. Formation of sludge, B. Removal of floating large objects, C. Settlement of heavy objects, D. Formation of Zoogleal layer', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]