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: Physiology
Major portion of coronary blood flow occurs during: 
Select and explain. 
A. Systole, B. Diastole, C. Not related to phases, D. It is variable
B: Diastole
Answer: B: Diastole 
Explanation: None