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: Pharmacology
A patient with cancer developed an 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 during radiotherapy in order to prevent radiation toxicity 
Select and explain. 
A. Vincristine, B. Dactinomycin, C. Cyclophosphamide, D. 6–Mercaptopurine
B: Dactinomycin
Answer: B: Dactinomycin 
Explanation: Anthracyclines and actinomycin-D (dactinomycin) can cause severe radiation toxicity. This is known as radiation recall syndrome.