A 50-yeаr-оld wоmаn with а histоry of seasonal allergies presents with a 2-week history of persistent cough, intermittent wheezing, and clear sputum. She denies fever or chest pain. She appears well but is mildly tachypneic with shallow breathing. Auscultation reveals expiratory wheezes and occasional crackles that partially clear with coughing. Percussion is resonant; tactile fremitus and egophony are normal.Which diagnosis is most likely?