Human activies that impact water cycle include

a. Use of toxic chemicals in agriculture and manufacturing run-off
b. A decreased use of water by animals
c. An increase of sedimentation of rivers
d. A decrease in the erosion of creek beds

a. Use of toxic chemicals in agriculture and manufacturing run-off

Explanation:

it is the only activity listed the rest are possible impacts

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.