What is the primary function of hemoglobin in the blood?

The primary function of hemoglobin in the blood is to transport oxygen from the lungs to the tissues. Hemoglobin is a protein found in red blood cells that binds to oxygen molecules inhaled into the lungs, allowing these molecules to be carried through the bloodstream and delivered to various cells and tissues throughout the body. This oxygen transport is critical for cellular respiration, which is the process by which cells produce energy. Without adequate levels of hemoglobin, oxygen delivery would be compromised, leading to potential energy deficits and affects on overall health.

Other functions suggested in the options, such as transporting nutrients, providing immunity, or assisting in blood clotting, are performed by different components of the blood. Nutrients are transported primarily by plasma; the immune response is carried out by white blood cells and antibodies; and various clotting factors and platelets are responsible for the blood clotting processes. Each component of blood plays a unique and essential role, but hemoglobin's specific and vital role is focused on oxygen transport.