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
Positive zone of enamel caries is the: 
Select and explain. 
A. Translucent zone, B. Dark zone, C. Body of the lesion, D. Surface zone
B: Dark zone
Answer: B: Dark zone 
Explanation: The dark zone
This lies adjacent and superficial to the translucent zone. It has been referred to as the ‘positive zone’ because it is usually present. This zone is formed as a result of demineralization and appears dark brown in ground sections examined by transmitted light after imbibition with quinolone.