What color is attributed to the oxygen-carrying pigment in red blood cells?

The oxygen-carrying pigment in red blood cells is hemoglobin, which is responsible for transporting oxygen from the lungs to the tissues of the body and returning carbon dioxide from the tissues back to the lungs. Hemoglobin contains iron, which directly binds to oxygen, giving red blood cells their characteristic red color. The presence of oxygen bound to hemoglobin is what leads to the bright red color of arterial blood.

Myoglobin, while similar to hemoglobin, is found in muscle tissues and aids in oxygen storage rather than transport. Chlorophyll is the green pigment found in plants involved in photosynthesis and not related to blood. Carotene is a pigment found in plants that can give an orange color, such as in carrots, and is also unrelated to blood oxygen transport. Thus, hemoglobin is distinctly recognized for its role and association with the red color in blood due to its oxygen-carrying capacity.