This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
[{'content': 'One gray of radiation is equal to - \nSelect and explain. \nA. 1 rad, B. 10 rad, C. 100 rad, D. 1000 rad', 'role': 'user'}, {'content': "Answer: C \nExplanation: The activity of radioactive material is the number of nuclear disintegration per unit of time. SI unit of radiation exposure - coulomb per kilogram (1Roentgen = 2.58x10-4 C/kg) absorbed dose - Gray (1 Gray = 100 rad) Dose equivalent - Sieve (Sv) (1 Sv = 100 rems) Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 804", 'role': 'assistant'}]