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: The most important factor in maintaining the hydration of cornea is the endothelium pump mechanism and therefore by maintaining the state of relative dehydration, it helps in maintains transparency.', 'role': 'assistant'}]