This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fundamental concepts, Subject name: Anaesthesia
[{'content': 'A mid tracheostomy is done over \nSelect and explain. \nA. 1st and 2nd tracheal ring, B. 2nd and 3rd tracheal ring, C. 3rd and 4th tracheal ring, D. 5th and 6th tracheal ring', 'role': 'user'}, {'content': 'Answer: B \nExplanation: a mid tracheostomy is done at 2nd and 3rd tracheal rings behind the isthumus,it is the operation of choice .', 'role': 'assistant'}]