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 prophylthiouracil ? \nSelect and explain. \nA. Prevents synthesis of thyroglobulin, B. Prevents iodine trapping, C. Prevents release of T4 & T3, D. Inhibits coupling', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Inhibits coupling", 'role': 'assistant'}]