<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 21-year-old man presents to his physician because he has been feeling increasingly tired and short of breath at work. He has previously had these symptoms but cannot recall the diagnosis he was given. Chart review reveals the following results:Oxygen tension in inspired air 150 mmHgAlveolar carbon dioxide tension 50 mmHgArterial oxygen tension 71 mmHgRespiratory exchange ratio 0.80Diffusion studies reveal normal diffusion distance. The patient is administered 100 oxygen but the patients blood oxygen concentration does not improve. Which of the following conditions would best explain this patients findings?? A: Pulmonary embolism, B: Pulmonary fibrosis, C: Septal defect since birth, D: Use of opioid medications, E: Vacation at the top of a mountain,  <response>: This is a medical question asking about a patient with symptoms of fatigue and shortness of breath. The key details are the gas exchange results showing low arterial oxygen tension that does not improve with 100 oxygen administration. This indicates an issue with oxygen transfer from the lungs to the bloodstream. The choices describe different pulmonary conditions that could potentially explain these findings. I need to choose the option that best matches a defect in oxygen transfer across the alveolar-capillary membrane.C: Septal defect since birth 