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': 'Corneal endothelial cell count is done by – \nSelect and explain. \nA. Specular microscopy, B. Keratometry, C. Gonioscopy, D. Slit lamp', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Specular microcopy is used for corneal endothelial density.', 'role': 'assistant'}]