What is the primary function of erythropoietin in the body?

Erythropoietin, a hormone primarily produced by the kidneys, plays a crucial role in the regulation of red blood cell production, a process known as erythropoiesis. When oxygen levels in the blood decrease, the kidneys release erythropoietin to stimulate the bone marrow to produce more red blood cells. This is essential for maintaining adequate oxygen transport throughout the body, particularly in response to conditions such as anemia or hypoxia.

The other options do not accurately represent the primary role of erythropoietin. While regulation of blood pressure, enhancement of iron absorption, and promotion of white blood cell production are important physiological processes, they are not directly related to the action of erythropoietin. The hormone's specific and primary function is to increase the production of red blood cells in response to oxygen demand, which is a critical aspect of ensuring proper tissue oxygenation and overall metabolic function.