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
[{'content': 'The neurotransmitter agent that is normally released in the SA node of the heart in response to increased blood pressure is: \nSelect and explain. \nA. Acetylcholine, B. Dopamine, C. Adrenaline, D. Noradrenaline', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]