This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Medicine
[{'content': 'Angina pectoris is best diagnosed by \nSelect and explain. \nA. History, B. ECG, C. Cardiac Enzyme, D. Echo', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. HistoryAngina Pectoris is best diagnosed by history.a. This is due to myocardial ischemia and presents as a central chest tightness or heaviness (Levine sign) which is brought on by exertion and relieved by rest.b. It may radiate to one or both arms, the neck, jaw or teeth. Atherosclerosis is the most common cause of CAD.c. ECG and Echo may be normal and cardiac enzyme are usually not raised in angina.', 'role': 'assistant'}]