Answer:
The term that best describes the function of blood when considering the presence of leukocytes and antibodies is "protection".
Step-by-step explanation:
Leukocytes, also known as white blood cells, play a crucial role in protecting the body against infection and disease by identifying and attacking foreign invaders. Antibodies, which are produced by certain types of white blood cells, also help to protect the body by recognizing and neutralizing harmful pathogens. Together, leukocytes and antibodies form an important part of the body's immune system, which helps to protect against a wide range of threats.