Final answer:
A nasal cannula delivers approximately 40% oxygen at a 6 LPM flow rate under optimal conditions. The correct option is closest to (B) 40%.
Step-by-step explanation:
A nasal cannula can deliver 44% of oxygen at a flow rate of 6 liters per minute (LPM) in optimal conditions. Options A, B, C, and D do not accurately represent this percentage. However, for practical purposes, the closest option provided is (B) 40%, which might be considered an approximation. It's important to ensure that patient requirements are met with both the correct flow rate and concentration of oxygen, and this knowledge is crucial for those in the medical field.