This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: COPD and Asthma, Subject name: Medicine
What is the best management option in a patient with COPD, with low SpO2 at rest? 
Select and explain. 
A. Quit smoking, B. Bronchodilators, C. Low flow Oxygen, D. Mucolytics
C: Low flow Oxygen
Answer: C: Low flow Oxygen 
Explanation: In COPD, non-uniform ventilation and ventilation-perfusion mismatching leads to localized vasoconstriction Supplemental oxygen abolishes this constriction, leading to improved ventilation/perfusion ratio. High flow oxygen is not tolerated as it leads to crusting, dryness and epistaxis. While continuous therapy is required for patients who show hypoxemia at rest, intermittent treatment during specific periods may be used for patients who demonstrate intermittent hypoxemia.