A 70-year-old ex-smoker with chronic cough and exertional dyspnoea undergoes spirometry. Post-bronchodilator FEV₁/FVC ratio is 0.55 and FEV₁ is 55% predicted. Which finding confirms the diagnosis of chronic obstructive pulmonary disease (COPD)?APost-bronchodilator FEV₁/FVC ratio <0.70BFEV₁ <80% predictedCIncreased total lung capacityDReduced diffusion capacity for carbon monoxide (DLCO)EReversibility of FEV₁ by >15% after bronchodilatorCheck my answer