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': 'In Valvular Aortic Stenosis poorest prognosis in indicated when - \nSelect and explain. \nA. Angina occurs, B. Syncope occurs, C. Dyspnea occurs, D. Palpitation occurs', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]