Students in mrs. nichols' ecology class noted that coastal regions in the state were changing. areas that had once been only occasionally submerged now remained underwater all year; even low tides did not uncover the once marshy areas. the ecology students hypothesized that the most likely reason for this change in sea level and therefore habitat was

Global warming / climate change resulting in the melting of glaciers causing a rise in sea level. 

The answer is b, as with an inference you make a statement with no evidence

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.