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
In radical neck dissection, which structure is not removed 
Select and explain. 
A. Cervical group of lymph nodes, B. Sternocleidomastoid muscle, C. Internal jugular vein, D. None of the above
D: None of the above
Answer: D: None of the above 
Explanation: None