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: Unknown
[{'content': 'Thyroid hormone receptor which is predominantly expressed in CNS/Brain - \nSelect and explain. \nA. a - 1, B. a - 2, C. b - 1, D. b - 2', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans- b - 1 Ref-', 'role': 'assistant'}]