Final answer:
Neutrophils produce cytokines that enhance the phagocytic activity of immune cells.
Step-by-step explanation:
Neutrophils are phagocytic cells that play a key role in the immune response. When neutrophils encounter pathogens, they release cytokines, which help other phagocytes recognize and destroy the foreign material. This process enhances the phagocytic activity of immune cells, ensuring efficient elimination of pathogens from the body. Therefore, the correct answer is A) Increases phagocytic activity.