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': 'Blood brain barrier is absent in ? \nSelect and explain. \nA. Adenohypophysis, B. Neurohypophysis, C. Hypothalamus, D. Thalamus', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Neurohypophysis", 'role': 'assistant'}]