An unsuccessful life history strategy would be associated with populations that:. A. Decrease in size over time.
B. Increase in size over time.
C. Either decrease or do not change in size over time.
D. Either increase or do not change in size over time.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.