Which of the following is a function of red blood cells?

Red blood cells, or erythrocytes, have a primary and essential function in the body: they carry oxygen from the lungs to the tissues and transport carbon dioxide from the tissues back to the lungs for exhalation. The mechanism behind this transportation relies on hemoglobin, a protein within red blood cells that binds to oxygen molecules. This capability is crucial for providing energy to cells throughout the body since oxygen is necessary for cellular respiration, a process that generates ATP, the energy currency of cells.

While other components of the blood, such as plasma and white blood cells, are responsible for transporting nutrients and fighting infections respectively, the specific role of red blood cells is focused on oxygen and carbon dioxide transport. They do not play a significant role in regulating body temperature either; that function is primarily managed through mechanisms involving blood flow and sweat production.