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': 'Out of the following hypersensitivity reactions, in which type a single dose of the antigen can act as both the sensitizing and shocking dose. \nSelect and explain. \nA. Anaphylaxis, B. Arthus reaction, C. Serum sickness, D. Contact dermatitis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]