Answer:
D. Cytokines
Explanation:
I would utilize Cytokines to recruit more leukocytes to the battle.
Cytokines are important chemical messengers that act via receptors in the immune system of the body. They are a group of proteins made by various immune cells. Immune cells communicate through Cytokines in regulating immune response
A living entity is referred to as an organism. In order of size: cell, tissue,organ,organism.