This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and PNS, Subject name: ENT
Recurrent or residual cancer of nasopharynx after super voltage radiotherapy is treated by: 
Select and explain. 
A. Intracavitary radioactive implants, B. Cryotherapy, C. Surgery, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: If nasopharyngeal carcinoma recurs or is not completely regressed after 6500-7000 cGy radiotherapy, it can be treated by any of the above modes. Surgery involves skull-base and is done in only selected cases.