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': 'Anaphylaxis refers to the \nSelect and explain. \nA. Severe reaction following  injection of protein solutions in a sensitized individual, B. Severe reaction following primary injection of protein solutions, C. State of immunity developed by repeated injections of any foreign substance, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: To elicit the anaphylactic reaction exposure to the allergens for the first time (priming) is necessary, the reaction can be seen on reexposure only.', 'role': 'assistant'}]