This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'Not a live vaccine \nSelect and explain. \nA. BCG vaccine, B. Salk vaccine, C. Measles vaccine, D. Yellow fever vaccine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Preparation of salk vaccine Virus is grown in monkey kidney cells and inactivated by formalin. Each dose of vaccine contains total 80 units of D antigen of all the three poliovirus serotypes. schedule 4 doses 1st 3 doses with 1-2 months gap, 4th booster dose is given 6-12 months after the 3rd dose.', 'role': 'assistant'}]