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 shape of head of a Gates Glidden drill is \nSelect and explain. \nA. Flame shaped, B. Cone shaped, C. Ball shaped, D. Diamond shaped', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]