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': "The corneal transparency is maintained by \nSelect and explain. \nA. Keratocytes, B. Bowman's membrane, C. Descement's membrane, D. Endothelium", 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. Endothelium', 'role': 'assistant'}]