question: Q:A 27-year-old man presents to the emergency department with a progressively worsening cough, wheezes, and chest tightness over the last 2 days. He has a history of moderate persistent asthma and his maintenance regimen consists of an inhaled corticosteroid, a long-acting beta-agonist, and albuterol as rescue therapy. He has not improved with his rescue inhaler despite increased use. He reports prior exposure to a person who had symptoms of a respiratory infection. His temperature is 37.4°C (99.3°F), blood pressure is 101/68 mm Hg, heart rate is 99/min, and respiratory rate is 32/min. Physical examination reveals widespread polyphonic wheezes but equal air entry. His oxygen saturation is 92% on room air. The presence of which of the following categorizes this patient’s condition as life-threatening?? 
  {'A': 'Peak expiratory flow rate (PEFR) >70%', 'B': 'Dyspnea that limits usual daily activity', 'C': 'Symptoms lasting for > 3 days after starting treatment', 'D': 'Respiratory alkalosis', 'E': 'Respiratory acidosis'},