Final answer:
Erythrocytes, or red blood cells, are not a type of white blood cell. White blood cells include mast cells, macrophages, and monocytes, which are part of the body's defense system.
Step-by-step explanation:
The option that is NOT an example of a white blood cell is D. erythrocytes. Erythrocytes, or red blood cells, are responsible for transporting oxygen throughout the body and do not have the capabilities that white blood cells have, such as phagocytosis or immune response activities. On the other hand, mast cells, macrophages, and monocytes are all types of white blood cells. Mast cells are involved in allergic responses and in the release of chemicals during physical injury, whereas macrophages and monocytes are involved in phagocytizing pathogens and in the body's immune response.