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
Normally, the rate of the heart beat in a human is determined by: 
Select and explain. 
A. The bundle of His, B. All cardiac muscle, C. The sinoatrial node, D. The cervical ganglion
C: The sinoatrial node
Answer: C: The sinoatrial node 
Explanation: None