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: Radiology
The most common radio-opaque mass at root apex of a vital tooth is due to: 
Select and explain. 
A. Hypercementosis, B. Condensing osteitis, C. Periapical cemental dysplasia, D. True cementoma
C: Periapical cemental dysplasia
Answer: C: Periapical cemental dysplasia 
Explanation: None