Which statement best describes the function of red blood cells (RBC)?

Red blood cells (RBCs) are primarily responsible for the transportation of oxygen from the lungs to the tissues throughout the body. This function is facilitated by hemoglobin, a protein found in high concentrations within red blood cells. Hemoglobin binds to oxygen in the lungs, where the oxygen concentration is high, and releases it in tissues where the concentration is lower. This oxygen transport is vital for cellular respiration, allowing cells to produce energy.

While red blood cells do have secondary roles, such as aiding in the transport of carbon dioxide back to the lungs for exhalation, their primary function remains the delivery of oxygen. Understanding this role is crucial in fields like cardiology and hematology, as it directly affects overall health and the functioning of bodily systems.