A client with chronic obstructive pulmonary disease (COPD) reports increased shortness of breath with activity. Which lest should the nurse schedule the client for evaluation of the symptoms?

A. A lung biopsy is invasive and not necessary for evaluating shortness of breath; it is typically used to diagnose lung diseases rather than evaluate functional status. B. A sweat test is used primarily for cystic fibrosis diagnosis and is not relevant to COPD. C. Antibody testing is not related to the evaluation of respiratory symptoms in COPD. D. Spirometry is the best test for assessing lung function and can help determine the severity of COPD and guide treatment.