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 bones are pneumatic, except: \nSelect and explain. \nA. Maxillary, B. Parietal, C. Frontal, D. Ethmoidal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Pneumatic bones are those bones which contain an air filled cavity within them.\xa0\nIn humans, they are seen in relation to the the nasal cavity – they enclose the paranasal sinuses.\xa0\nPneumatic bones are – maxilla, frontal bone, sphenoid and ethmoid.', 'role': 'assistant'}]