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: Pharmacology
[{'content': 'Drug of choice for acute adrenal insufficiency is ? \nSelect and explain. \nA. Oral prednisone, B. IV hydrocortisone, C. IV betamethasone, D. IV dexamethasone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]