What is the primary function of red blood cells?

The primary function of red blood cells (RBCs) is indeed closely associated with the containment of hemoglobin, which is a crucial protein found within these cells. Hemoglobin binds oxygen in the lungs and carries it to tissues throughout the body, playing a vital role in oxygen transport. This function is central to the overall respiratory and circulatory systems.

While red blood cells are involved in transporting both oxygen and carbon dioxide, the defining characteristic and function are largely dependent on their hemoglobin content. Without hemoglobin, red blood cells would be unable to efficiently facilitate the transport of these gases, which is critical for maintaining cellular metabolism and overall physiological function.

The other options present functions that do not pertain directly to the role of red blood cells. Maintenance of blood pressure is primarily managed by the circulatory system and is not a direct function of red blood cells. The production of white blood cells is conducted by the bone marrow and is related to the immune system, which is separate from the primary role of red blood cells. While red blood cells do participate in the transport of carbon dioxide, the presence and function of hemoglobin remain the essential reason why red blood cells exist and perform their critical role in the body.