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: Pharmacology
The neurotransmitter agent that is normally released in the SA node of the heart in response to increased blood pressure is: 
Select and explain. 
A. Acetylcholine, B. Dopamine, C. Adrenaline, D. Noradrenaline
A: Acetylcholine
Answer: A: Acetylcholine 
Explanation: None