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
Unstable Angina, True is 
Select and explain. 
A. Chest pain occurs at rest., B. Pain lasts for 10 minutes., C. Pain subsides on rest., D. All of the above.
A: Chest pain occurs at rest.
Answer: A: Chest pain occurs at rest. 
Explanation: Unstable Angina

Chest Pain at rest
Pain > 10 min
Pain at rest.