A pathogen is:. a. a protein that displays other proteins on the surface of different cells in the body.
b. a cell that grows and divides out of control.
c. a virus, bacterium, or microorganism that can cause disease.
d. a protein that can identify infectious agents in the body.

The answer is obviously C

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Ibelieve the answer is relative humidity  because it makes more sense that way. solar flares usually occur in space it doesn't affect the earth, well it could but it wont make a significant damage.  latitude is land it doesnt do anything. prevailing winds, i dont know the correct meaning for this but i doubt that affects the land so it has to be relative humidity.