Answer: The answer is (a). There are specific indications for the use of endotracheal intubation. These include, need to initiate mechanical ventilation, protection of the airway, inadequate oxygenation by less invasive ways, prevention of aspiration following pulmonary toileting and hyperventilation for the treatment of raised intracranial tension. Failure of nasal prongs to improve the Pa02 is not an indication for intubation as other less invasive methods may be tried such as continuous positive airway mask and bilevel positive airway ventilation.