What is the yellow pigment produced from the breakdown of red blood cells that is usually processed by the liver?

The yellow pigment produced from the breakdown of red blood cells is bilirubin. When red blood cells reach the end of their lifecycle, hemoglobin—the protein that carries oxygen—undergoes a process in which it is broken down. The heme portion of hemoglobin is converted into bilirubin. This bilirubin then travels to the liver, where it is processed and excreted in bile. This process is essential for the elimination of excess heme and the recycling of iron.

In addition, bilirubin can give the skin and the whites of the eyes a yellow tint when it accumulates excessively in the body, a condition known as jaundice. This characteristic is especially pertinent in medical diagnostics, as it can indicate various health issues related to liver function or red blood cell breakdown.

The other options represent different substances and processes. Hemoglobin is the oxygen-carrying component of red blood cells, cholesterol is a type of lipid important for cell membranes and hormone synthesis, and melanin is the pigment responsible for skin, hair, and eye color. Each plays vital roles, but none are directly involved in the breakdown of red blood cells to produce bilirubin.