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: Pathology
The cytoprotective agent used for the prevention of xerostomia in patients undergoing head and neck radiotherapy is 
Select and explain. 
A. Valacyclovir, B. Amifostine, C. Glycopyrrolate, D. Naproxen
B: Amifostine
Answer: B: Amifostine 
Explanation: None