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
Trismus in oral cancer patients is severe in those treated with - 
Select and explain. 
A. Surgery and Radiotherapy, B. Chemotherapy alone, C. Surgery alone, D. Not related to treatment
A: Surgery and Radiotherapy
Answer: A: Surgery and Radiotherapy 
Explanation: Restriction to mouth opening, including restrictions caused by trauma, surgery or radiation.
Implications : Reduced nutrition due to impaired mastication, difficulty in speaking, and compromised oral hygiene.
Often observed in persons who have received radiation to the head and neck, in conjunction with difficulty in swallowing.
Limited jaw mobility can result from trauma, surgery, radiation treatment, or even TMJ problems.
Radiation that affects the temporomandibular joint, the pterygoid muscles, or the masseter muscle, is most likely to result in trismus.
Some patients who have not received radiation treatment may develop trismus secondary to scarring and edema after surgery.