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
A patient who has been given tumoricidal dose of radiotherapy recently reports to dental clinic with painful carious exposed mandibular first molar with periapical abscess. The treatment of choice should be: 
Select and explain. 
A. Extraction of the offending tooth, B. Root canal treatment if possible, C. No treatment should be given, D. Incision and drainage of abscess
B: Root canal treatment if possible
Answer: B: Root canal treatment if possible 
Explanation: None