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
[{'content': 'Which of the following acts as the major neurotransmitter in substantia nigra \nSelect and explain. \nA. Dopamine, B. Noradrenaline, C. Acetylcholine, D. Serotonin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In substantia nigra, dopamine is the major neurotransmitter.', 'role': 'assistant'}]