i think the answer may be blood diamonds
It's d it has to be because the Japan has to do something
Basically the Earth is layered because of gravity. The earth formed in the molten state. The liquid iron which is very dense fell to the center. The rest of the earth is made up of silicate materials with SiO2 being the main component.
hope this helps!
Humans tend to congregate and form settlements around areas that are rich with natural resources such as forests and rivers, because these locations support life and the economy.