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
Anaphylaxis refers to the 
Select and explain. 
A. 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
A: Severe reaction following  injection of protein solutions in a sensitized individual
Answer: A: Severe reaction following  injection of protein solutions in a sensitized individual 
Explanation: To elicit the anaphylactic reaction exposure to the allergens for the first time (priming) is necessary, the reaction can be seen on reexposure only.