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: Social & Preventive Medicine
[{'content': 'Antisera is obtained from \nSelect and explain. \nA. Guinea pig, B. Horse, C. Rat, D. Rabbit', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Antisera (Antitoxins): Materials prepared in animals; non-human sources like horses', 'role': 'assistant'}]