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: Medicine
Factor I and H deficiency causes 
Select and explain. 
A. Typical HUS, B. Atypical HUS, C. TTP, D. Acute TTP
B: Atypical HUS
Answer: B: Atypical HUS 
Explanation: A typical HUS (Non - epidemic, diarrhea negative) : common cause factor H & I deficiency.