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
[{'content': 'Radiotherapy associated caries is due to irradiation of which part most probably? \nSelect and explain. \nA. Tongue, B. Maxillary sinus, C. Parotid gland, D. Lower jaw', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]