Occupational Lung Disease - Simple Silicosis

A 52-year-old stone quarry worker with 25 years of occupational exposure to crystalline silica dust presents with gradually progressive exertional dyspnoea (MMRC grade 2), dry cough, and mild chest tightness. He is a non-smoker. Chest X-ray shows multiple small rounded opacities (1–3 mm diameter) in the upper and middle zones with eggshell calcification of hilar lymph nodes, consistent with simple nodular silicosis. His spirometry is performed after bronchodilator administration. The flow-volume loop shows a narrow, homogeneously scaled-down curve without concavity of the expiratory limb. Which of the labeled spirometry patterns **B** represents the findings most consistent with his diagnosis?