<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 15-year-old boy and his mother were referred to a pulmonology clinic. She is concerned that her son is having some breathing difficulty for the past few months, which is aggravated with exercise. The family is especially concerned because the patients older brother has cystic fibrosis. The past medical history is noncontributory. Today, the vital signs include: blood pressure 11980 mm Hg, heart rate 90min, respiratory rate 17min, and temperature 37.0C 98.6F. On physical exam, he appears well-developed and well-nourished. The heart has a regular rate and rhythm, and the lungs are clear to auscultation bilaterally. During the exam, he is brought into a special room to test his breathing. A clamp is placed on his nose and he is asked to take in as much air as he can, and then forcefully expire all the air into a spirometer. The volume of expired air represents which of the following?? A: Expiratory reserve volume, B: Functional residual capacity, C: Tidal volume, D: Total lung capacity, E: Vital capacity,  <response>: This is a clinical vignette about a 15-year-old boy with possible breathing difficulties, whose older brother has cystic fibrosis. The question asks about interpreting the results of a pulmonary function test, specifically spirometry. The test described involves the patient inhaling maximally and then forcefully exhaling into a spirometer, which measures the volume of expired air. This maneuver measures the vital capacity, which is the total volume of air that can be maximally exhaled after a maximal inhalation. E: Vital capacity 