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
Best treatment of refractory peri-anal fistula in crohn's disease:- 
Select and explain. 
A. Fistulectomy, B. Infliximab, C. Olasalizine, D. Mesalamine
B: Infliximab
Answer: B: Infliximab 
Explanation: 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.