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
Prinzmetal angina is- 
Select and explain. 
A. Angina after extreme exertion, B. Caused due to atherosclerotic blockade, C. Caused due to spasm of artery, D. Calcium channel blockers not effective
C: Caused due to spasm of artery
Answer: C: Caused due to spasm of artery 
Explanation: None