The answer is D, white blood cells.
The main function of white blood cells is to defense the body from bacteria or other pathogens. There's 2 main kinds of white blood cells, lymphocytes and phagocytes. Lymphocytes mainly produce antibodies that can kill bacteria or any pathogens, and phagocytes can ingest the pathogens directly.
Therefore, since the white blood cells can protect our body, they're part of our immune system.
Meiosis is the process of cell division that produces eggs and sperm for sexual reproduction. <span />
I’m pretty sure it is Sediments I think
There are many environmental negative direct outcomes of unused excess nitrogen from nitrogenous fertilizers. One of these is eutrophication. Eutrophication is the excessive richness of nutrients in a water body as a result of fertilizer run offs from the land, which causes a dense growth of plants in the water. Other negative outcomes are: green house effects, acid rain and contamination of underground water which has negative effects on human health.