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
The zone of dentin most recently formed and uncalcified is known as: 
Select and explain. 
A. Mantle dentin, B. Circumpulpal dentin, C. Predentin, D. Secondary dentin
C: Predentin
Answer: C: Predentin 
Explanation: None