This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammatory Bowel Disease, Subject name: Medicine
[{'content': "Best treatment of refractory peri-anal fistula in crohn's disease:- \nSelect and explain. \nA. Fistulectomy, B. Infliximab, C. Olasalizine, D. Mesalamine", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Infliximab is effective in CD patients with refractory perianal and enterocutaneous fistulas, with 68% response rate (50% reduction in fistula drainage) and a 50% complete remission rate. Reinfusion, typically every 8 weeks, is necessary to continue therapeutic benefits in many patients.', 'role': 'assistant'}]