Answer: The correct answer for the fill in the blank is Phagocytes.
Phagocytes are the White blood cell which help in eliminating the chances of infection by attacking foreign particles in the body. They do this with the help of a process, which is called as phogocytosis.
In this process, they first ingest the harmul particles like bacteria ( in the form of food vacuoles, phogosomes) and then digest them using hydrolytic enzymes.
By doing so, they completely eliminate the chances of infection in the body.
Example of phagocytes- Macrophages, dendritic cells, and neutophils.