The function of the red blood cells is to

Red blood cells (RBCs) or erythrocytes are specialized cells in the body that have a main function of transporting oxygen from the lungs to the rest of the body tissues. RBCs contain a protein called hemoglobin that binds to oxygen in the lungs and carries it through the bloodstream to the body's tissues. Once the oxygen is delivered, RBCs pick up carbon dioxide, which is a waste product produced by the body's cells, and transport it back to the lungs to be exhaled. Therefore, the function of the red blood cells is to transport oxygen to the cells and remove carbon dioxide from them.