C. Birds eating seeds from plants
The earth's crust is very important to human beings not only because they live in it but because of the socio-economic benefits it offers them. ... Some of these less dense rocks, such as granite, are common in the continental crust but rare to absent in the oceanic crust. Both the continental and oceanic crust mantle.
The best example is their amazing system of roads. The Incas built roads across the length and width of their empire. To create routes through steep mountain ranges, they carved staircases and gouged tunnels out of rock. They also built suspension bridges over rivers.
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