Nuclear reactions, such as fusion and fission, convert A- very small amounts of energy into significant particles of matter.
B- large amounts of matter into negligible amounts of energy.
C- very small amounts of matter into significant amounts of energy.
D- large amounts of energy into very small particles of matter.

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.