Final answer:
The best nursing positioning technique to assist a patient with COPD who is receiving supplemental oxygen 2.0 nasal cannula is a high-Fowler's position, which promotes optimal lung expansion.
Step-by-step explanation:
The best nursing positioning technique to assist a patient with COPD who is receiving supplemental oxygen 2.0 nasal cannula is to place the patient in a high-Fowler's position (option b).
The high-Fowler's position allows for optimal lung expansion by elevating the head of the bed to a 90-degree angle, promoting a better airflow and reducing the work of breathing.
Other positions mentioned in the options, such as supine (lying flat), right side-lying, and flat on the stomach, may restrict chest expansion and hinder breathing in patients with COPD.