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: Radiology
[{'content': 'The structure marked with arrows is: \nSelect and explain. \nA. Empty trabeculae, B. Incisive foramen, C. Incisive canal, D. Midline suture', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]