C
Organ systems perform many of their life functions; example: respiration, digestion, excretion, transmitting nerve impulses, etc
After the macrophage fails the Helper T Cell stimulates the B cells if pathogen is extracellular and Cytotoxic T Cells if the pathogen is intracellular. Once the pathogen is killed the B Cells create Memory B Cells and the Killer T Cells create memory T Cells.
Answer:
A,B,F
Explanation
because these are the most imporatant things on the list