<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 23-year-old woman with no significant past medical history currently on oral contraceptive pills presents to the emergency department with pleuritic chest pain. She states that it started today. Yesterday she had a trip and returned via plane. Her temperature is 98F 36.7C, blood pressure is 11766 mmHg, pulse is 105min, respirations are 14min, and oxygen saturation is 98 on room air. Physical exam reveals tachycardia, a normal S1 and S2, and clear breath sounds. The patients lower extremities are non-tender and symmetric. Chest pain is not reproducible with position changes or palpation but is worsened with deep breaths. Which of the following is the most appropriate next test for this patient?? A: Chest radiograph, B: CT angiogram, C: D-dimer, D: Ultrasound of the lower extremities, E: Ventilation-perfusion scan,  <response>: This is a clinical vignette about a 23-year-old woman with pleuritic chest pain and recent air travel, concerning for pulmonary embolism. The key findings are pleuritic chest pain, tachycardia, and recent air travel, which increase the risk for pulmonary embolism. The appropriate next test would be one that can help diagnose or rule out pulmonary embolism. A chest radiograph can sometimes detect abnormalities suggestive of pulmonary embolism but has low sensitivity. CT angiogram is the gold standard test for diagnosing pulmonary embolism. D-dimer is a lab test that is sensitive but not specific for pulmonary embolism. Lower extremity ultrasound may detect deep vein thrombosis but does not evaluate the lungs directly. A ventilation-perfusion scan can help diagnose pulmonary embolism but CT angiogram is more sensitive and specific.C: D-dimer 