This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrine, Subject name: Pathology
[{'content': "Vanillyl mandelicacid (VMA) increased in \nSelect and explain. \nA. Parathyroidism, B. Pheochromocytoma, C. MEN-1, D. Addison's disease", 'role': 'user'}, {'content': 'Answer: B \nExplanation: (Pheochromocytoma) (798- Basic Robbins 8th)PHEOCHROMOCYTOMA - "Rules of 10s"*** Demonstrating characteristic nests of cells ("Zellballen") with abundant cytoplasm* The definite diagnosis of malignancy in pheochromocytoma is based exclusively on the presence of metastasis*** Diagnosis demonstration of increased excretion of free Catecholamines and their metabolites such as vanillylmandelic acid and metanephrines**', 'role': 'assistant'}]