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': 'What is the effect of doubling the diameter of a cantilever spring? \nSelect and explain. \nA. Strength increases by 4 times, Springiness increases by 8 times, B. Strength decreases by 4 times, Springiness decreases by 8 times, C. Strength decreases by 8 times, Springiness increases by 16 times, D. Strength increases by 8 times, Springiness decreases by 16 times', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]