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
[{'content': 'Caries detection dye can stain the following except: \nSelect and explain. \nA. Granular necrotic tissue, B. Dry, leathery dentin, C. Reversibly denatured collagen, D. Irreversibly denatured collagen', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]