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: Medicine
[{'content': 'A 25-year-old male presents with weakness, occasional vomiting hypotension, skin and mucous membrane pigmentation. The diagnosis can be best established by - \nSelect and explain. \nA. Metyrapone test, B. Basal plasma cortisol levle, C. 24- hour urinary 17-Ketosteroid, D. ACTH stimulation test', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]