This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Radiation treatment planning, Subject name: Radiology
Not a radiosensitizing drug - 
Select and explain. 
A. 5-Fu, B. BUDR, C. Cyclophosphamide, D. Hydroxyrea
C: Cyclophosphamide
Answer: C: Cyclophosphamide 
Explanation: Ans. is 'c' i.e., Cyclophosphamide RadiosensitizersA) Hypoxic cell radiosensitizers1) Nitroimidazoles:- Metronidazole, Misonidazole, Etanidazole, Nimorazole, Pimonidazole2) Anticancers:- Actinomycin D (Dactinomycin), Bleomycin, Cisplatin, Doxorubicin, 5-FU, Fludarabine, Gemcitabine, Hydroxyurea, Paclitaxel, Mitomycin - C, Topotecan, Vinorelbine.3) Hyperbaric oxygen (most potent)B) Non hypoxic cell radiosensitizers1) Haloginatedpyrimidines:- BUdR, IUdR.Cisplatin and 5-FU are two of the most commonly used radiosensitizing agents.