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': 'MgCl2 is added to polio vaccine because of the following - \nSelect and explain. \nA. Potentiates the vaccine, B. Vaccine can be kept at higher temperatures, C. Preservative, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: molar MgCl2 is used to dtabilise the vaccine against heat inactivation REF:ANATHANARAYANAN MICROBIOLOGY NINTH EDITION PAGE.488', 'role': 'assistant'}]