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': 'Pivoting movement better resisted by a tooth preparation if: \nSelect and explain. \nA. Diameter is smaller, B. Diameter is large, C. Diameter is large and length is small, D. Do not depend on diameter of tooth', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]