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
The etiology of amyloidosis is - 
Select and explain. 
A. Automimmune, B. T-cell mediated, C. B cell mediated, D. Unknown
D: Unknown
Answer: D: Unknown 
Explanation: Ans. is 'd' i.e., Unknown