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: Microbiology
[{'content': 'Child acquires antibody against ABO antigen at which age \nSelect and explain. \nA. At bih, B. 6 Months, C. 2 Years, D. 5 Years', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., 6 Months", 'role': 'assistant'}]