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': 'Mechanism of action of bromocriptine is: \nSelect and explain. \nA. Agonism at D2 receptors, B. Antagonism at D2 receptors, C. Antagonism at D1 receptors, D. Antagonism at α receptors', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]