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
[{'content': 'Which type of FSGS has worst prognosis \nSelect and explain. \nA. Perihilar variant, B. Collapsing variant, C. Glomerular tip variant, D. Cellular variant', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Collapsing variant has the worst prognosis.\nIt is also associated with HIV.', 'role': 'assistant'}]