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 patient presents with tachycardia, BP<100mm Hg systolic and postural hypotension. Diagnosis is - \nSelect and explain. \nA. Vasovagal attack, B. Diabetic neuropathy, C. Shy drager syndrome, D. Bleeding peptic ulcer', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]