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: ENT
[{'content': 'A 65 year old man presented with vocal cord palsy. He is a pan chewer since childhood. On examination, his abducting function of vocal cord is impaired. The nerve affected is: \nSelect and explain. \nA. External laryngeal nerve, B. Recurrent laryngeal nerve, C. Mandibular nerve, D. Vagus nerve', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The sole abductor of the vocal cords is the posterior cricoarytenoid muscle which is innervated by recurrent laryngeal nerve. Innervation of the Vocal Cord: Muscle Nerve Adductors (lateral cricoarytenoid, thyroarytenoid, interarytenoids) Recurrent laryngeal (adductor branch) Posterior cricoarytenoid Recurrent laryngeal (abductor branch) Cricothyroid External laryngeal', 'role': 'assistant'}]