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': 'Enameloplasty \nSelect and explain. \nA. 1/3 of enamel is removed, B. 1/2 of enamel is removed, C. 1/4 of enamel is removed, D. Fissures are broadened and made self-cleansable', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]