This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
Which of the following is the most commonly used MR sequence for non-contrast angiography? 
Select and explain. 
A. Time-of-flight (TOF), B. Phase contrast, C. TRUFI, D. Aerial spin labeling
A: Time-of-flight (TOF)
Answer: A: Time-of-flight (TOF) 
Explanation: .