<prompt> A 28-year-old pregnant woman develops sudden onset of dyspnea and tachycardia with no other physical findings. Which of the following is the most likely diagnosis?pulmonary emphysemapulmonary embolismmyocardial infarctionventricular tachycardia  <response>: Sudden onset of unexplained dyspnea is the most common and often the only symptom of pulmonary embolism. Findings on physical examination may be deceptively normal, but tachycardia is a consistent finding. Pleuritic chest pain and hemoptysis suggest a peripheral embolism adjacent to the pleura. 