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
When taking a reline impression for an upper denture,
which is the most common error? 
Select and explain. 
A. Failure to remove undercuts, B. Improperly rounded peripheries, C. Improper establishment of a post dam area, D. Changed centric occlusion
D: Changed centric occlusion
Answer: D: Changed centric occlusion 
Explanation: None