What is the primary function of white blood cells?

The primary function of white blood cells is to fight infections. These cells, or leukocytes, play a crucial role in the immune system by identifying and attacking pathogens such as bacteria, viruses, and fungi. They are essential for the body’s defense mechanism, as they not only combat current infections but also help in the formation of immunological memory. This allows the body to respond more effectively to future infections by the same pathogens.

The other options focus on different roles within the blood. For instance, the transport of oxygen is primarily the function of red blood cells, which contain hemoglobin that binds to oxygen for delivery to tissues. The clotting of blood involves platelets and various proteins that help prevent excessive bleeding in the event of injury. Lastly, carrying nutrients is a function closely associated with plasma and red blood cells. Thus, while all these elements are vital for overall health and function, white blood cells are specifically key to the immune response.