30 cases of a diarrheal disease occurred among residents of a rural midwestern community between july 1 and july 31, 2016 (usual rate: 0-1 per year). this is an example of a/an:

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.