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: Anatomy
[{'content': 'All of the following are present beneath floor of 4th ventricle except \nSelect and explain. \nA. Hypoglossal nucleus, B. Facial nucleus, C. Abducens nucleus, D. Facial nerve', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Facial colliculus, a swelling in floor of 4th ventricle is formed by facial nerve looping around abducens nucleus. So facial nucleus doesn’t form the floor of 4th ventricle.', 'role': 'assistant'}]