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: Skin
[{'content': 'An increased incidence of vitiligo is found in: \nSelect and explain. \nA. Psoriasis, B. Nutritional deficiency, C. Old age, D. Diabetes mellitus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. Diabetes mellitus', 'role': 'assistant'}]