<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 58-year-old man is diagnosed with right lower lobe pneumonia and has been admitted to a tertiary care hospital. His laboratory investigations suggest that he acquired an infection from the hospital where he underwent an elective abdominal surgery 3 weeks ago. His past medical records reveal a history of deep vein thrombosis and pulmonary embolism one year prior. After a steady clinical improvement over 5 days of inpatient treatment, he develops a cough, breathlessness, and hemoptysis on the 6th day. His temperature is 38.6C 101.5F, the pulse is 112min, the blood pressure is 13084 mm Hg, and the respiratory rate is 28min. A general examination shows the presence of edema over the right leg and tenderness over the right calf region. Auscultation of the chest reveals localized crackles over the left mammary region and right infrascapular region. However, his heart sounds are normal, except for the presence of tachycardia, and there are no murmurs. Which of the following is the investigation of choice as the immediate next step in this patients management?? A: Plasma D-dimer, B: Serum brain natriuretic peptide, C: Echocardiography, D: Contrast-enhanced computed tomography CECT of chest, E: Ventilation-perfusion scanning,  <response>: This is a clinical vignette describing a 58-year-old man with a history of hospital-acquired pneumonia after recent abdominal surgery. He also has a prior history of DVT and PE. On day 6 of treatment, he develops worsening respiratory symptoms and signs of a new DVT. The question asks about the next best diagnostic test.Based on the acute worsening of his respiratory status and prior DVTPE history, pulmonary embolism should be high on the differential. Edema and tenderness of the right calf raise suspicion for a new DVT. D-dimer, BNP, echocardiography are not first-line tests for suspected PE. CECT chest would be the investigation of choice to evaluate for pulmonary embolism.D: Contrast-enhanced computed tomography CECT of chest 