Which of the following describes the role of erythrocytes?

Erythrocytes, commonly known as red blood cells, primarily function to transport oxygen from the lungs to the tissues and organs throughout the body. They contain hemoglobin, a protein that binds to oxygen, allowing for efficient delivery of this essential gas. In addition to carrying oxygen, erythrocytes also play a role in transporting carbon dioxide, a waste product of metabolism, from the tissues back to the lungs for exhalation.

While other cells and components of the blood are responsible for the immune response, blood clotting, and maintenance of pH balance, erythrocytes are distinctly specialized for their role in gas exchange. Thus, the emphasis on their primary function in the context of this question is well-founded as transporting oxygen is crucial for cellular respiration and overall metabolic processes.