Which component primarily gives blood its red color?

The component that primarily gives blood its red color is hemoglobin. Hemoglobin is a protein found in red blood cells, and it binds to oxygen molecules in the lungs and carries them throughout the body. The iron content in hemoglobin plays a critical role in this process; when oxygen binds to iron, it forms a complex that appears red. This red color is especially prominent when blood is oxygenated, giving arterial blood its bright red appearance.

In comparison, plasma is the liquid component of blood that primarily consists of water, electrolytes, proteins, and waste products and does not contribute to the red color. Platelets are cell fragments involved in blood clotting and have no color contribution. White blood cells are part of the immune system and help fight infection, but they also do not affect blood's overall color. Thus, it is hemoglobin specifically that is responsible for the characteristic red hue of blood.