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': 'Blindness in a child is most commonly due to - \nSelect and explain. \nA. Keratomalacia, B. Congenital cataract, C. Glaucoma, D. Injuries', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Keratomalacia is due to vitamin A deficiency.\n\n"Vitamin A deficiency is the most common cause of blindness in children in India". __\xa0Philip Reily\n"Vitamin A deficiency is the single most important cause of blindness in children". — Wykoff', 'role': 'assistant'}]