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
Example of an immune complex hypersensitivity reaction is: 
Select and explain. 
A. Atopic allergy, B. Serum sickness, C. Transfusion reaction, D. Contact dermatitis
B: Serum sickness
Answer: B: Serum sickness 
Explanation: None