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: Dental
[{'content': 'Underlying pathology of Nevus anemicus is: \nSelect and explain. \nA. Autoimmune destruction of melanocytes, B. Arrest of migration of melanocytes, C. Abnormal vasoconstriction, D. Defect in tyrosinase enzyme', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Nevus anemicus presents as a localized area of skin blanching and hypopigmentation because of abnormal vasoconstriction due to increased sensitivity of blood vessels to catecholamines.', 'role': 'assistant'}]