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': 'How much luting agent is required for cementation of crown? \nSelect and explain. \nA. 3/4th filled slightly upto the margin, B. 1/4th filled, C. 1/2 filled, D. Full to prevent bubble', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]