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: Physiology
Pain is conducted by: 
Select and explain. 
A. A-alpha fibers, B. A-beta fibers, C. A-gamma fibers, D. A-delta fibers
D: A-delta fibers
Answer: D: A-delta fibers 
Explanation: None