Final answer:
The late manifestation of end-stage Chronic obstructive pulmonary disease (COPD) is the increased use of accessory muscles for breathing, as the primary muscles for respiration can no longer meet the oxygen demands of the body.
Step-by-step explanation:
Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterized by chronic poor airflow and impaired gas exchange. In the late stages of this terminal illness, the patient suffers from several symptoms including persistent shortness of breath, increased use of accessory muscles for breathing, and typically produces sputum which can be clear or purulent. The alveoli breakdown and their elasticity is reduced, leading to air trapping and a reduced surface area for gas exchange. Use of accessory muscles for breathing indicates the disease has progressed and the patient is working harder to breathe. The decreased efficacy of the lungs causes low oxygen levels and an elevated level of carbon dioxide in the blood. This is detectable via a spirometry test, which measures the rate and volume of air breathed in and out.
Among the provided options, the late manifestation of end-stage COPD is C) Use of accessory muscles for breathing. This happens as a compensatory mechanism when the diaphragm and other primary muscles of respiration are no longer sufficient to meet the body's demands for oxygen. Increased exercise tolerance and decreased dyspnea at rest would be highly unlikely in a patient with end-stage COPD, while a clear and productive cough does not specifically indicate the late stage of the disease and can be present at any stage.