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
Stress concentration in Root dentin is least with: 
Select and explain. 
A. Smooth tapered post., B. Serrated tapered post, C. Smooth parallel post., D. Serrated parallel post
C: Smooth parallel post.
Answer: C: Smooth parallel post. 
Explanation: None