Eosinophilic Bronchitis (Non-asthmatic)

A 52-year-old woman presents to the respiratory clinic with a 4-month history of chronic dry cough. She denies wheeze, dyspnea, or nocturnal symptoms. Physical examination is unremarkable. Spirometry shows FEV1 92% predicted, FVC 95% predicted, and FEV1/FVC ratio 0.78. Methacholine challenge test is negative (PC20 > 16 mg/mL). Induced sputum analysis reveals eosinophils 8% of nonsquamous cells. The clinical and functional profile shown by the pattern marked **A** in the diagram is most consistent with which diagnosis?