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
Isovolumetric relaxation phase of the cardiac cycle ends with 
Select and explain. 
A. Peak of C waves, B. Opening of AV valve, C. Closure of semilunar valve, D. Beginning of T waves
B: Opening of AV valve
Answer: B: Opening of AV valve 
Explanation: None