This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
[{'content': 'The physical half life of radioactive iodine 131 is \nSelect and explain. \nA. 8 hours, B. 8 days, C. 16 days, D. 60 days', 'role': 'user'}, {'content': 'Answer: B \nExplanation: RADIOACTIVE IODINE The stable isotope of iodine is 127I. Its radioactive isotope of medicinal impoance is: 131I physical half-life of iodine 131 is 8 days. Mech of action:- 131I emits X-rays as well as b paicles. latter are utilized for their destructive effect on thyroid cells. 131I is concentrated by thyroid, incorporated in colloid--emits radiation from within the follicles. The b paicles penetrate only 0.5-2 mm of tissue. The thyroid follicular cells are affected from within, undergo pyknosis and necrosis followed by fibrosis when a sufficiently large dose has been administered, without damage to neighbouring tissues. Ref:- kd tripathi; pg num:-255', 'role': 'assistant'}]