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
Which type of FSGS has worst prognosis 
Select and explain. 
A. Perihilar variant, B. Collapsing variant, C. Glomerular tip variant, D. Cellular variant
B: Collapsing variant
Answer: B: Collapsing variant 
Explanation: Collapsing variant has the worst prognosis.
It is also associated with HIV.