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
All the heart valves are open during which stage of cardiac cycle: 
Select and explain. 
A. Systolic ejection, B. Isovolumetric relaxation, C. Isovolumetric contraction, D. None of the above
D: None of the above
Answer: D: None of the above 
Explanation: None