Answer:
The correct answer would be white blood cells.
White blood cells (WBC) or leukocytes are the primary cells of the immune system.
These cells protect our body from a foreign invader or infectious agent.
On the basis of lineage, these cells are mainly of two types:
- Myeloid cells: monocytes, neutrophils, eosinophils, and basophils
- Lymphoid cells: B cells, T cells, and natural killer cells.
Once an infectious agent enters our body, the immune cells get activated and fight back the infectious agent
