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: Pathology
[{'content': "Pigmentation occurs in oral cavity and skin in all of the\nfollowing except: \nSelect and explain. \nA. Peutz-jeghers syndrome, B. Addison's syndrome, C. Cushing syndrome, D. Albright syndrome", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]