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': 'Prinzmetal angina is- \nSelect and explain. \nA. Angina after extreme exertion, B. Caused due to atherosclerotic blockade, C. Caused due to spasm of artery, D. Calcium channel blockers not effective', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]