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': "Hamarlopia is seen in \nSelect and explain. \nA. Oguchi's disease, B. High myopia, C. Vitamin A deficiency, D. Congenital deficiency of cones", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Hamarlopia (day blindness) is due to congenital deficiency of cones\xa0 and central corneal and central lenticular Opacities.', 'role': 'assistant'}]