I would have to go with Sewage mostly because it smells and because it can really hurt the environment. Plants can die and it just is gross to smell. So this would definitely pollute the earth. I hope this helped! :D
Ocean water is most saline in dense seawater.
answer: b. in dense seawater.
~ Drought hazard is generally high for semiarid areas, such as Northeastern and Southern South America, Northern, Southwestern and Horn of Africa, Central Asia, Australia, West U.S. and the Iberian Peninsula; and low for tropical regions, such as the Amazon, Central Africa and Southern Asia
Answer: I think the answer is C
Explanation: It is not B because if they moved closer to all of the resources such as water food and shelter then that wouldn't be a bad thing for them, It is also A not because if they did move away from large factories then that would be technically a good thing so the kids in danger of dangerous things, and it is also not D because if they were to move near the center of a country then they can start their own farms. So therefore my answer is C because if they did this then they wouldn't have very many natural resources to rely on.
I HOPE THIS HELED YOU OUT! IF NOT SO SORRY!!!