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: Dental
[{'content': 'Figure B shows: \nSelect and explain. \nA. Spinal tap needle, B. Shortened Spinal tap needle assembled with H file, C. Side vent needle for irrigation, D. Needle with file for simultaneous filing and irrigation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]