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: Physiology
In the cardiac cycle diagram, when does the first hea sound occur 
Select and explain. 
A. Point A, B. Point B, C. Point C, D. Point D
A: Point A
Answer: A: Point A 
Explanation: When ventricle begin to contract isovolumetrically the mitral & tricuspid valves close producing First hea sound Ref: Metting, Physiology pretest and review, 14th edition