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': 'Half life of Technetium is \nSelect and explain. \nA. 6 hours, B. 12 hours, C. 24 hours, D. 26 hours', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. 6 hours Half life (tin) of radium (Ra226)is 1602-1626 years (longest)Q; Cesium (137Cs) is 30 yearsQ; Cobalt (60Co) is 5.2 yearsQ; iridium (1921r)is 74.5 daysQ; Iodine (P31)is 8 daysQ; 1123 is 13 hoursQ; technitium (Tc99) is 6 hoursQ; and 1132 is 2.3 hoursQ.', 'role': 'assistant'}]