Which statement most accurately describes Chronic obstructive pulmonary disease?

A. A clinical spectrum caused by acute myocardial ischaemia, including unstable angina and myocardial infarction. B. Acute infection of the meninges requiring urgent antimicrobial treatment. C. Acute pancreatic inflammation commonly presenting with severe epigastric pain and elevated pancreatic enzymes. D. Persistent airflow limitation commonly related to smoking or noxious exposure.