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': 'Foramen of Magendie is the central opening of - \nSelect and explain. \nA. Lateral ventricle, B. 4th ventricle, C. 3rd ventricle, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans-B', 'role': 'assistant'}]