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: Pathology
[{'content': 'Large antigen - antibody reaction is required to cause - \nSelect and explain. \nA. Serum sickness, B. Ahus reaction, C. Uicaria, D. Anaphylactic-reaction', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Ahus reaction", 'role': 'assistant'}]