This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pediatrics
Pheochromocytoma is the disease of: 
Select and explain. 
A. Pituitary gland, B. Adrenal medulla, C. Pancreas, D. Adrenal cortex
B: Adrenal medulla
Answer: B: Adrenal medulla 
Explanation: b. Adrenal medulla(Ref: Nelson's 20/e p 2227-2729, Ghai 8/e p 525)Pheochromocytoma is a neoplasms of chromaffin cells in medulla that release catecholamines.