<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 67-year-old man is brought to the emergency department because of increasing shortness of breath that began while playing outdoors with his grandson. He has a history of asthma but does not take any medications for it. On arrival, he is alert and oriented. He is out of breath and unable to finish his sentences. His pulse is 130min, respirations are 23min and labored, and blood pressure is 11070 mm Hg. Physical examination shows nasal flaring and sternocleidomastoid muscle use. Pulmonary exam shows poor air movement bilaterally but no wheezing. Cardiac examination shows no abnormalities. Oxygen is administered via non-rebreather mask. He is given three albuterol nebulizer treatments, inhaled ipratropium, and intravenous methylprednisolone. The patient is confused and disoriented. Arterial blood gas analysis shows:pH 7.34Pco2 44 mm HgPo2 54 mm HgO2 saturation 87Which of the following is the most appropriate next step in management?? A: Endotracheal intubation, B: Intravenous theophylline therapy, C: Continuous albuterol nebulizer therapy, D: Intravenous magnesium sulfate therapy, E: Flexible bronchoscopyn,  <response>: This is a clinical vignette about a 67-year-old man with a history of asthma presenting with an acute exacerbation. He is in respiratory distress with tachypnea, use of accessory muscles, poor air movement, and hypoxemia despite oxygen therapy and bronchodilators. The arterial blood gas shows respiratory acidosis. This indicates that he is not responding adequately to initial therapy and requires further intervention to support his breathing. The options include more aggressive bronchodilator therapy, methylxanthines, magnesium, intubation, and bronchoscopy. Intubation is the most definitive way to ensure adequate oxygenation and ventilation in a patient not responding to medical therapy. The other options may be reasonable but are not as aggressive at ensuring ventilation and oxygenation.A: Endotracheal intubation 