This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head & Neck, Subject name: Anatomy
[{'content': 'Choose the appropriate lettered structure in this MRI scan showing a sagittal section through the head and neck. A tumor of which structure can be removed through the transsphenoidal approach following the septum of the nose through the body of the sphenoid? \nSelect and explain. \nA. A, B. B, C. C, D. D', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (a) The pituitary gland can be reached through the transsphenoidal approach following the septum of the nose through the body of the sphenoid.', 'role': 'assistant'}]