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: Pathology
Bacteria free zone of dentinal caries is 
Select and explain. 
A. a)Zone of decomposed dentin, B. Zone of bacterial invasion, C. Zone of decalcification, D. Zone of dentinal sclerosis
D: Zone of dentinal sclerosis
Answer: D: Zone of dentinal sclerosis 
Explanation: None