52. How does the immune system differentiate a pathogen from body cells?
A. Pathogens have especially weak cell membranes that the immune system can break.
B. Pathogens and body cells have different surface proteins, or antigens, that the immune system recognizes.
C. Body cells release a variety of chemicals that deactivate the immune system.
D. Pathogens are significantly smaller and reproduce more rapidly than body cells.