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: Ophthalmology
[{'content': "Metabolically most active layer of cornea is: \nSelect and explain. \nA. Endothelium, B. Stroma, C. Descemet's membrane, D. Epithelium", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Epithelium', 'role': 'assistant'}]