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
All the following diseases contain abnormal immunoglobulin except: 
Select and explain. 
A. Multiple myeloma, B. Reactive arthritis, C. Seligman's disease, D. Franklin's disease
B: Reactive arthritis
Answer: B: Reactive arthritis 
Explanation: Multiple myeloma – Bence Jones proteins
Seligmann's disease – Alpha chain
Franklin's disease – Gamma chain