This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nuclear medicine, Subject name: Radiology
Isotope of iodine used in treatment for brachytherapy of prostate carcinoma? 
Select and explain. 
A. I-127, B. I-125, C. I-131, D. I-124
B: I-125
Answer: B: I-125 
Explanation: Isotopes in medicine: I 131 I 125 I 124 I 123 T1/2 8 DAYS 60 DAYS 4 DAYS 13 HOURS USES RADIOABLATION SYSTEMIC OF THYROID CANCER BRACHYTHERAPY FOR PROSTATE CANCER RADIOIMMUNOASSAY POSITRON EMITTER PET SCAN THYROID SCINTIGRAPHY Point to be remembered: ISOTOPE USED FOR TREATING PAPILLARY CARCINOMA OF THYROID IS IODINE-131 (I131)