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': 'Xerosis/ Xerophthalmia is due to deficiency of: March 2013 (h) \nSelect and explain. \nA. Vitamin K, B. Vitamin E, C. Vitamin D, D. Vitamin A', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D i.e. Vitamin A', 'role': 'assistant'}]