This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oesophagus, Subject name: Surgery
[{'content': 'What is the instrument shown below? \nSelect and explain. \nA. Urethral dilator, B. Tracheal dilator, C. Aneurysm needle, D. Urethral dilator', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. (b) Tracheal dilator* Used during tracheostomy* Smooth and round tip (Not sharp)* Tips bent at right angles to rest of the instrument* No lock or clasp* This is known as Trousseau's Tracheal dilator* Helps to widen trachea while inserting tube", 'role': 'assistant'}]