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: Anatomy
Which of the following is situated in the upper pa of Crista terminalis ? 
Select and explain. 
A. AV node, B. Bundle of his, C. Right Bundle branch, D. SA node
D: SA node
Answer: D: SA node 
Explanation: SA node