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: Anaesthesia
Indications of tracheostomy are 
Select and explain. 
A. Flail chest, B. Head injury, C. Tetanus, D. All
D: All
Answer: D: All 
Explanation: A i.e. Flail chest; B i.e. Head injury; C i.e. Tetanus