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
Delphian lymph nodes act as sentinal lymph nodes in: 
Select and explain. 
A. Nasopharyngeal carcinoma, B. Laryngeal cancer, C. Parotid cancer, D. All of the above
B: Laryngeal cancer
Answer: B: Laryngeal cancer 
Explanation: Delphian lymph nodes are pretracheal / paratracheal lymph nodes which are sentiner lymph nodes in laryngeal cancer & thyroid cancer.