This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
[{'content': 'Range of current used by biphasic defibrillator \nSelect and explain. \nA. 30-100 joules, B. 100-300 joules, C. 300-1000 joules, D. 1000-2000 joules', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Modern units deliver a biphasic shock, during which shock polarity is reversed mid-shock. This reduces the total energy required to depolarise the hea. The energy of first and second shocks should be 150joules and thereafter up to 200joules. Reference Harrison 20th edition pg 1576', 'role': 'assistant'}]