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: Surgery
[{'content': 'Which of the following is the First vein ligated during thyroidectomy? \nSelect and explain. \nA. Superior thyroid vein, B. Middle thyroid vein, C. Inferior thyroid vein, D. Thyroid ima vein', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Middle thyroid vein present only in 30 - 35% individuall. and it is the first vein ligated during thyroidectomy. (note : Thyroid ima is direct pranch from arch of anrta supplying thyroid gland which is present in some individuale).', 'role': 'assistant'}]