Final answer:
The Y-axis on the oxyhemoglobin curve represents the relative Hb-oxygen saturation. The line where letter Y is located refers to a concentration of oxygen typically found in arteries.
Step-by-step explanation:
The Y-axis on an oxyhemoglobin curve represents the relative Hb-oxygen saturation.
Based on the information provided, the line where letter Y is located would refer to a concentration of oxygen typically found in arteries.
Arteries carry oxygenated or oxygen-rich blood away from the heart to various parts of the body.