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: Gynaecology & Obstetrics
[{'content': 'III perineal tear is involvement of : \nSelect and explain. \nA. Vaginal mucosa, B. Urethral mucosa, C. Levator ani muscle, D. Anal sphincter', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Anal sphincter', 'role': 'assistant'}]