This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Thinnest bone is a pa of which bone \nSelect and explain. \nA. Frontal, B. Ethmoid, C. Sphenoid, D. Temporal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The lamina papyracea (or orbital lamina) is a smooth, oblong bone plate which forms the lateral surface of the labyrinth of the ethmoid bone in the skull. The plate covers in the middle and posterior ethmoidal cells and forms a large pa of the medial wall of the orbit. The ethmoid bone is an anterior cranial bone located between the eyes.] It contributes to the medial wall of the orbit, the nasal cavity, and the nasal septum. The ethmoid has three pas: cribriform plate, ethmoidal labyrinth, and perpendicular plate.', 'role': 'assistant'}]