Which of the following is NOT a function of leukocytes?

Leukocytes, or white blood cells, play a crucial role in the immune system, primarily focusing on defending the body against infections and foreign invaders. While they are critical in fighting infections (as part of the body's response to pathogens), producing antibodies, and clearing dead tissue, their functions do not include transporting oxygen.

Oxygen transport is the primary responsibility of erythrocytes, or red blood cells. These cells contain hemoglobin, which binds to oxygen in the lungs and carries it to tissues throughout the body. Consequently, the statement that leukocytes are involved in this function is incorrect, as they do not have the necessary structure or role in the oxygen transport mechanism.