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
What is the effect of doubling the diameter of a cantilever spring? 
Select and explain. 
A. 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
D: Strength increases by 8 times, Springiness decreases by 16 times
Answer: D: Strength increases by 8 times, Springiness decreases by 16 times 
Explanation: None