This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Brain , Subject name: Anatomy
[{'content': 'Floor of third ventricle is formed by all except \nSelect and explain. \nA. Tuber cinereum, B. Posterior perforated substance, C. Tegmentum, D. Anterior pituitary', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The floor is formed from before backwards by:Optic chiasmTuber cinereumInfundibulumMamillary bodiesPosterior perforated substanceTegmentum of midbrain(Ref: Vishram Singh textbook of clinical neuroanatomy second edition pg 137)', 'role': 'assistant'}]