This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Brainstem, cerebellum and ventricles, Subject name: Anatomy
[{'content': 'In which pa of the brain is the cerebral aqueduct is found? \nSelect and explain. \nA. Diencephalon, B. Mesencephalon, C. Metencephalon, D. Myelencephalon', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Cerebral aqueduct of sylvius is found in the Midbrain (mesencephalon); it connects the third ventricle to the fouh ventricle. Midbrain is derived from mesencephalon.', 'role': 'assistant'}]