This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea, Subject name: Ophthalmology
[{'content': "Corneal transparency is maintained by: \nSelect and explain. \nA. Bowman's membrane, B. Endothelium, C. Keratocytes, D. Descemet's membrane", 'role': 'user'}, {'content': 'Answer: B \nExplanation: The primary mechanism controlling stromal hydration is a function of the corneal endothelium which actively pumps out theelectrolytes and water flows out passively. Endothelium consists of a single layer of flat polygonal (mainly hexagonal) epithelial cells (misnamed as endothelium) which on slit-lamp biomicroscopy appear as a mosaic.', 'role': 'assistant'}]