The Immune System is built on millions of cells called

White blood cells: lymphocytes, neutrophils, and monocytes

Explanation:

Lymphocytes are processed in the bone marrow and then migrate to the lymphoid organs. The cells of the immune system are white blood cells: lymphocytes, neutrophils, and monocytes.

The immune system comprises of many biological structures and processes within an organism that provides resistance to infection and toxins.

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

c should be the answer