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: Medicine
[{'content': 'Drug of choice associated with pheochromocytoma \nSelect and explain. \nA. Phenoxybenzamine, B. Phentolamine, C. Labetalol, D. Esmolol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Drugs used in management of pheochromocytoma DOC is Phenoxybenzamine Ref- pubmed.com <a href=" <p>Ref', 'role': 'assistant'}]