This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
[{'content': 'The following condition is caused by the deficiency of? \nSelect and explain. \nA. vitamin A, B. vitamin B, C. Vitamin C, D. vitamin D', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Bitot&;s spots are the buildup of keratin located superficially in the conjunctiva of human&;s eyes. They can be oval, triangular or irregular in shape. The spots are a sign of vitamin A deficiency and associated with drying of the cornea. ref : harrisons 20th ed', 'role': 'assistant'}]