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: A i.e. Keratomalacia', 'role': 'assistant'}]