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
Which vital structure is preserved during radical dissection - 
Select and explain. 
A. Vagus nerve, B. Submandibular gland, C. Strenocleidomastoid, D. Internal jugular vein
A: Vagus nerve
Answer: A: Vagus nerve 
Explanation: None