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: Dental
[{'content': "A lady came with unilateral white skin lesions with leukotrichia. Shows 2 white spots 1 x 1cm each over left side of chin and neck. Diagnosis? \nSelect and explain. \nA. Segmental vitiligo, B. Piebaldism, C. Waardenburg's syndrome, D. Regional vitiligo", 'role': 'user'}, {'content': 'Answer: A \nExplanation: .', 'role': 'assistant'}]