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 present at all of the following sites except \nSelect and explain. \nA. Habenular nucleus, B. Subfornical organ, C. Cerebellum, D. Pontine nucleus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Structures outside blood brain barrier\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Posterior pituitary\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Ventral part of median eminence of hypothalamus\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Area postrema\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Organ vasculosum of lamina terminalis (OVLT)\n\xa0\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Subfornical organ', 'role': 'assistant'}]