This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rectum and anal canal, Subject name: Surgery
[{'content': 'Seton used in fistula in ano surgery is: \nSelect and explain. \nA. Dissecting seton and draining seton, B. Cutting seton and Dissolving seton, C. Cutting seton and draining seton, D. Fibrosing seton and Dissecting seton', 'role': 'user'}, {'content': "Answer: C \nExplanation: SETONS A seton is a ligature of silk, nylon, silastic or linen. Used for making, drainage, cutting or staging. A high fistula may be conveed into a low fistula by setons Setons are useful in the management of Complex anorectal fistulas with risk of incontinence or poor healing Patients with Crohn's disease Immunocompromised (HIV) and incontinent patients Patients with chronic diarrheal states Anterior fistula in women", 'role': 'assistant'}]