0. How might the channelization of rivers affect populations in river ecosystems? A. Aquatic species might find new food sources.
B. Aquatic species might require different nutrients.
C. Aquatic species might adapt to land environments.
D. Aquatic species might lose the conditions they need to survive.

only b 

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.