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': 'Left sides vocal cord palsy is commonly due to - \nSelect and explain. \nA. Left hilar bronchial carcinoma, B. Mitral stenosis, C. Thyroid malignancy, D. Thyroid surgery', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Unilateral left abductor paralysis is most commonly due to a bronchial carcinoma at the left hilum.', 'role': 'assistant'}]