A21-year-old college senior presents to the clinic reporting shortness of breath and a nonproductive nocturnal cough. she states she used to feel this way only with extreme exercise, but lately she has felt this way continuously. she denies any other upper respiratory, gastrointestinal, and urinary symptoms and says she has no chest pain. her past medical history is significant only for seasonal allergies, for which she takes a nasal steroid spray; she takes no other medications. she has had no surgeries. her mother has allergies and eczema; her father has high blood pressure. she is an only child. she denies smoking and illegal drug use but drinks three to four alcoholic beverages per weekend. she is a junior in finance at a local university and has recently started a job as a bartender in town. on examination she is in no acute distress. temperature is 98.6, blood pressure is 120/80, pulse is 80, and respirations are 20. head, eyes, ears, nose, and throat examinations are essentially normal. inspection of her anterior and posterior chest shows no abnormalities. on auscultation of her chest, there is decreased air movement and a high-pitched whistling on expiration in all lobes. percussion reveals resonant lungs. which disorder of the thorax or lung does this presentation best describe?