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': 'A patient with cancer received extreme degree of radiation toxicity. Further history revealed that the dose adjustment of a particular drug was missed during the course of radiotherapy. Which of the following drugs required a dose adjustment in that patient during radiotherapy in order to prevent radiation toxicity – \nSelect and explain. \nA. Vincristine, B. Dactinomycin, C. Cyclophosphamide, D. 6 – Mercaptopurine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Actinomycin - D (Dactinomycin) is well is well known radiosensitizer. So its dose should be reduced during radiotherapy to prevent radiation toxicity.', 'role': 'assistant'}]