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: Radiology
Radiotherapy associated caries is due to irradiation of which part most probably? 
Select and explain. 
A. Tongue, B. Maxillary sinus, C. Parotid gland, D. Lower jaw
C: Parotid gland
Answer: C: Parotid gland 
Explanation: None