This is a typical grassland food web. it is also a small picture of an important cycle on earth: the carbon cycle. man can impact the carbon cycle in a negative way. all but one example below would negatively impact the carbon cycle. identify it.

a) planting a field of wheat
b) a factory with smoke stacks
c) the local landfill burning trash
eliminate
d) paved streets with many cars on the roads

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.

is this a psat question, if so do not cheat try your best.