Asthma Reversibility on Spirometry

A 28-year-old woman with a 6-month history of intermittent dyspnea, nocturnal cough, wheezing, and chest tightness triggered by exercise, cold air, and allergen exposure presents for spirometry. Pre-bronchodilator (BD) FEV1 is 2.10 L (68% predicted) with FEV1/FVC 0.65. After 400 mcg salbutamol via spacer, post-BD FEV1 increases to 2.62 L (85% predicted), representing a 520 mL (24.8%) increase from baseline. The post-BD FEV1/FVC ratio normalizes to 0.72. The flow-volume loop shows resolution of the pre-BD scooped expiratory limb. The spirometric pattern marked **A** in the diagram—post-BD FEV1 increase ≥12% AND ≥200 mL from baseline—is the hallmark of which diagnosis?