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: Surgery
[{'content': 'Which of the following structure is preserved in Type I Modified radical neck dissection? \nSelect and explain. \nA. Sternocleidomastoid, B. Spinal accessory nerve, C. Level IX lymph node, D. Internal juglar Nein', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Modified radical neck dissection involves removal of I - V lymph nodes &\xa0\nIn type 1: Spinal accessory nerve is preserved.\nIn type 2: Internal juglar vein is preserved.\nIn type 3: Sternocleidomastoid.', 'role': 'assistant'}]