This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Conjunctiva, Subject name: Ophthalmology
[{'content': 'Blindness in child is most commonly due to \nSelect and explain. \nA. Keratomalacia, B. Congenital cataract, C. Glaucoma, D. Injuries', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most common cause of childhood blindness is vitamin A deficiency Refer: Khurana 6th edition page number 382', 'role': 'assistant'}]