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: Biochemistry
[{'content': 'Keratosis is a feature of deficiency of \nSelect and explain. \nA. Vit A, B. Vit C, C. Vit D, D. Folic acid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]